As the gang sailed away from Blood Bath Bay, and headed towards Kaine Island, Bentley revealed the plan that he, Clockwerk, and Penelope had worked together to create, as well as several back up ideas that would allow them to bypass a number of obstacles that were around the island. The plan was simple; they were going to dock the ship behind some rocks and avoid being detected, where Sly and Carmelita would make their way to what appeared to be the main docking area for Dr. M's own ships, before using the path the trio had selected, thus allowing the others to assist them along the way, if they needed assistance. Everyone was, for the most part, going to be given codenames for this operation, just in case someone was listening to their frequency when they reached their destination, and both Sly and Carmelita, since they would be heading towards the Vault together, were going to be called 'the Ball'. It looked like a good plan, the best they could have come up with given the time and resources that were available to them at the moment, and the duo soon found that the gang was in agreement with all the ideas that had been laid on the table. In addition to all of them, and all that they had with them, Penelope arranged for the gangs biplanes to be brought out to them, where Diz stored them inside the ship with his chaotic magic... something that they simply went along with and didn't question.
Despite the fact that only two of them were going to be making their way to the Vault, and figure out how they were supposed to open the door if Dr. M wasn't able to do that with the number of years he had to drill and set up his fortress, everyone agreed that the original gang, meaning Sly, Bentley, Murray, Derpy, Gilda, Diz, and Carmelita, would be the first ones inside the Vault, allowing the others to clean up the rest of the defenses and defeat Dr. M.
When they arrived at Kaine Island, and docked the ship in the area that Bentley and the others deemed appropriate, Sly and Carmelita headed out for the other dock while the rest of the gang moved into position, making sure that they were ready to clear their own objectives when Bentley called for them to do something. As such Sly and Carmelita moved through the area and knocked out a few guards in the process, before coming to an area in front of a wall that allowed them to pause and make sure that everyone was ready, including Gilda, Derpy, and Diz, but once everyone confirmed that they were ready the duo moved forward and continued on their way. It wasn't long before they reached their first obstacle, as there were guard posts in the way and Penelope sent in her RC Chopper to dislodge them, allowing the duo to continue forward as she removed the second and third one, showing that her skills were exactly what she had claimed when she was chatting with Bentley before the ACES Competition. That was followed by the Guru finding a random guard and rammed him into the radio tower that would serve as the walkway for Sly and Carmelita to get closer to the lab that Clockwerk had discovered in his study of the fortifications, back when he was scanning the place, before they found something else that needed to be removed. The Panda King, hearing that the duo needed assistance, launched a powerful firework into the air and knocked down the metal cage that Sly wanted him to take out, smashing open the path into the lab and allowing the duo to continue down into the area that would take them to the vault.
After arriving in the lab, and smashing through a fan to do so, Dimitri showed them that he had found what Bentley has asked him to find, as he fired on the exterior targets and deactivated the laser walls that happened to be blocking their path, but as they reached the top of the elevator, however, they paused as Dr. M and one of his guards walked onto it and started talking as they moved towards the top of the tower... though while they weren't happy with Dr. M, as he ended up killing the guard for not changing the code from '1-2-3', they gladly took the information.
When they reached the top of the tower Dr. M had to go back down into the lab, as part of Dimitri's goal was to cause water to fill the lab and distract their enemy, and it seemed to work as the elevator went back down as Sly and Carmelita jumped off it, allowing them to go across the wire walkway to get close to the Vault door. Unfortunately, when they were close to their target, they somehow triggered the alarm and were forced to run faster as they reached the area that the combination lock was located in, where Sly input the code and turned off the alarm, as well as pulled the drills off the door and opened the way for them to approach it. It was in that moment, however, that Sly and Carmelita noticed that the large golden door had a slot where a Cooper Cane could be placed for a moment, and more like the one that Sly carried since the other four had different dimensions than his did, but that was when he slipped his cane into the slot and heard the sound of something unlocking as the door started to unlock before their eyes... only for Dr. M to arrive, via some sort of flying device that was attached to his head, and fire a powerful bolt of power at the door from the same device, forcefully closing the door before he turned on Sly and Carmelita.
The gang heard Dr. M declare that, because he owned the deed to this island, a deed that Sly reminded him that he stole from his father's will, that Sly and his gang was trespassing and that the key to the Cooper Vault, the one thing that he was missing, now belonged to him as well, something that he demanded Sly hand over before he contacted the authorities and had them arrested, even though the gang knew that such a thing would never happen. Bentley showed up behind Dr. M and loosed a dart into the device that allowed him to fly, allowing Sly and Carmelita to follow after him as they made their way back into the lab and out through the tunnel they had used to get into the tower that let them get near the Vault door. Somehow Dr. M had enough time to detach himself from the damaged device that Bentley had hit, make his way to something that was entirely different, and drop down in the area that was between them and where the ship was located, revealing a large mutated monster that was resistance to a large deal of pain and Sly even used his cane to force open the creature's mouth, before it tossed the cane out into the water and grabbed onto him with the intent to crush him as the others worked to save him.
It was in the following moments that Derpy, commanding the power of the lightning, flew into the area and surprised Dr. M by channeling several powerful bolts of lightning into the creature's head, forcing the mad scientist to detach from the creature and flee as the monster fell to the ground, before Bentley, Carmelita, and Derpy carried Sly back to the ship so he could rest and recover from what happened to him, while they focused on getting his cane back and figuring out how to get back to the Vault door.
As it turned out the cane happened to attach to an electromagnet buoy that was out in the water, preventing many members of the gang from actually doing anything because of their metallic gear and Diz, being the only one that could use any sort of magic that might help them, told Bentley that she coudn't just grab the cane while the buoy was still active, meaning that this task fell to the Guru. The plan was simple, the Guru was going to take control of the local sharks and lead them to the buoy, where they would attack the device and force the cane off of it, though since Dr. M had filled a good portion of the water with mines, which Diz had moved to prevent their ship from being hurt, he would need to dodge the mines and get the sharks to their destination. Once that happened, however, Bentley, Penelope, and Clockwerk knew that the cane would fly into the water, meaning that it would be up to Dimitri to recover the cane once the buoy was offline, to which he acknowledged the orders and prepared himself foe when it was his turn to take to the field, while at the same time the Guru headed off and started persuading the sharks to assist them.
As the Guru worked with the sharks, and made sure to get them to his target, Diz used her own chaotic powers and tried to channel a more healing aspect of them, but she quickly found out that her power wasn't suited for this sort of thing, to which they simply stayed near Sly and made sure that he was healed before anything happened.
"We're lucky Derpy acted as quickly as she had, otherwise Sly might have ended up with a concussion," Carmelita said, standing near Bentley as they watched the Guru work his magic, though the reason she wasn't with Sly was because she was more focused on getting back at Dr. M for what he had done.
"Dr. M is smarter than what we gave him credit for," Bentley added, as he wasn't expecting the mutated monsters that the mandrill was responsible for creating, so he didn't have to pay a substantial amount of money while he was getting nothing from the Vault, despite the fact that he had ordinary guards as well, "We need to be careful from this point forward, as he's likely to go after the cane as well, and there's no telling what sort of creatures he's prepared in case someone tries to break into his fortress, like we just did."
Carmelita opened her mouth to say something, but then stopped when the Guru brought the final pack of sharks to the buoy and caused the entire thing to tear itself apart, flinging him back towards the ship, and landing safely on the deck, while at the same time throwing the cane into the water, where Dimitri pulled his mask on and dived for it. The rest of the gang listened as Dimitri chased after the cane, through the passage that it was being pulled through, and then informed them that Dr. M knew that they would have dislodged the cane from where it was stuck, as he was now standing in front of Dimitri, using an underwater monster of his own design that also allowed him to breathe without the same gear that their friend was using, and seemed in the mood to kill someone. Since they couldn't actually see the monster this time around, as they hadn't had the time to outfit Dimitri's suit with a camera for taking pictures or shooting videos, they put their faith in Dimitri and listened as Dr. M insulted him and offered him a position on his payroll, as it he believed that he was actually going to be able to open the Cooper Vault and claim what wasn't his, while also letting them know that he was in possession of Sly's cane right now. Fortunately for them Dimitri, despite his lack of skill, once again proved that he was a natural with the scuba gear, as he was able to outmaneuver the monster that he was fighting and pushed Dr. M into a corner, where he was eventually forced to detach from the creature, as it tore itself apart and died, before fleeing to the surface... where the gang could hear him proclaim that they might control the water, but he controlled the skies.
Something that offset the terribleness of losing the cane to Dr. M was that Sly, despite his injuries, was up and about, as he said that he felt fine and was ready for anything, though Carmelita insisted that he get a few more minutes of rest, especially since Bentley and Penelope were in the process of using one of the Panda King's fireworks to launch her newly upgraded RC Car onto a drone patrol pipe... where she intended on hunting down the drone, stealing their power from their smashed bodies, and then use that power to fry the targeting matrix of the guided missiles that were around the fortress, where Clockwerk was the one who gave them that information once more.
Penelope smiled as her RC Car took to the field once more, touching down on the patrol pipe that was the start of the three towers she needed to take out, and she immediately started hunting down the drones that she needed to take out, using the newly added bumper feature on the sides of the tires to knock the drones into submission before she siphoned their energy into her vehicle. Once she had enough power from the first group of drones, and Bentley confirmed it by lowering the jump gate with a command from his computer, Penelope sent her RC Car flying through the air and used the power to tear through the first of her three targets, before landing on the next patrol pipe and starting all over again on a whole new track. From there it was only a matter of minutes before she had gathered a second batch of siphoned energy and used the second jump ramp to fly into the air, smashing the second target to pieces, before she landed on the third patrol pipe and started hunting down the remaining drones so she could knock out the guided missiles, as they would threaten the next stage of their plan... and it wasn't long before she let her RC Car sail through the air and smash through her final target, allowing the vehicle to return to the ship without a hint of damage on it.
Bentley then revealed that, with the towers taken out, that they had the chance for air superiority and had Diz bring out the biplanes, allowing Sly and Carmelita, their pilots, to take to the air as Gilda flew along with them, because since she was gifted with the power over wind she'd be able to help them quite easily. Their targets were the sensors on the missile turrets, which would only be exposed after a missile was fired, so they'd have to avoid the incoming attacks and then fire at their target, but since there were three of them, and only fourteen targets, it was a simple matter for Sly, Carmelita, and Gilda to take out the sensors before the turrets even knew what hit them. That was followed by a large squad of shielded bat like creatures, another of Dr. M's creations most likely, that took to the skies and attacked them, but Bentley informed both Sly and Carmelita that they weren't useless in this might, as they had a newly added missile feature that would be able to assist them in taking out these enemies, while Gilda could just sharpen her Wind Blades and tear through them since magic was something that Dr. M had clearly never encountered before. Once the three of them had taken care of those creatures, however, was when the last airborne threat came to attack them, as in the large whale-dragonfly hybrid that was covered in robotic parts... and, as they found out when he started calling out to them in a mocking tone, Dr. M was also plugged into the monstrosity and was heading for the Vault door with the cane.
As it turned out Dr. M had the monster firing seeker rounds at them, which were painful if they let one of them fire their missiles at them, to which Sly and Carmelita took turns exchanging targets, as Sly would start with Dr. M and Carmelita would fire at the seekers, before changing it up every so often. Gilda, on the other hand, followed after them and eventually grew tired of the seeker missiles being used against her family, to which she used the wind around her and started hacking apart the seekers before they had a chance to open up, before landing on the monster's back and started tearing apart the pieces that were allowing to to do what it was doing. Fortunately, even though it hadn't been her intention to do this, Gilda's attacks caused Dr. M to come up and see what was going on, to which he took a blast of wind to the face and was knocked off the monster that he had been plugged into, but not before Gilda was able to reclaim the item that they had been fighting over.
"Sly! I've got your cane!" Gilda said over the binocucom, which was also tied into the communications for the biplanes, though at the same time she turned her hand and knocked the creature out of the sky, causing it to crash into the other side of the island, opposite of the side that the ship was on, and she flew off towards the Vault door as Sly and Carmelita jumped out of their seats and followed after her with their paragliders, allowing Penelope to seize control of the biplanes and safely touch them down before they were damaged.
"Thanks for catching it." Sly replied, though once he, Carmelita, and Gilda touched down in front of the Vault door he was reunited with his cane, before he turned towards the large golden door in front of them and knew what they were going to do, "Well then, I guess it's time to meet the past."
"Don't worry Sly, we're on our way!" Murray called out, reminding them that the rest of the original gang, and that even included Clockwerk, were coming to join them so they could see what was inside the Vault, though at the same time Sly smiled and opened the Vault door, allowing it to separate into two halves and open all the way... while also revealing an elevator that would take them to their destination.
Sly never bothered to question Murray as to how he, Bentley, Derpy, Diz, and Clockwerk were going to get up here, as three of them had the ability to fly, but it appeared that the Panda King was more than willing to use his guided fireworks to launch them up to the ramp that was right in front of the Vault door... though as the van landed, and drove up to the elevator so they could all descend into the depths, they heard Bentley stating that they were never doing that again. When they reached the bottom, however, they discovered a number of ancient raccoon shaped statues, cane shaped statues, the legendary Cooper insignia carved into the stone floor and made out of an entirely different stone that rested in the new hole, and a metallic door, in the infamous raccoon shape, resting at the far edge of the room with a rotting bridge in front of it, indicating where they needed to go next.
"Sorry Bentley, Murray, it looks like the six of us will have to move ahead with you guys." Sly said, as he had been hoping that he could show the others what was inside the Vault, as he had never been here before, but as it turned out it was him and his immediate family.
"Do it, Sly." Bentley replied, to which he gestured to the entire area that was around them, as he knew why such a place had been built, and it wasn't just to hide the legendary Cooper Treasure, "This place was built for you guys. We'll hold down the fort here."
Sly nodded as he, Carmelita, Derpy, Gilda, Diz, and Clockwerk approached the gap and crossed over to the door that was in front of them, knowing that it was time to see what the other members of their family line had left for them, and maybe even learn something as they exploded the Vault.