A few years had passed, and after too many disappointments, the Cutie Mark Crusaders group has fallen apart. The fillies abandoned hope in getting their cutie marks by constantly trying something new, and instead followed the path of standard, boring careers. Their lives are about to take a big twist as they get on track of a serious crime.

The red sun hasn’t fallen beyond the horizon for many generations, and the steel grey clouds that remained after the Storm are the only thing that prevents Equestria from being scorched to death.

Cornerstone does his best to make a living in a gods forsaken city called Zone Two. He doesn’t care what secrets lie behind the impenetrable mirror wall. But there are other ponies out there, who would sacrifice their lives to unveil the mystery…

Hints!

Mystery and adventure, now with books!

Twilight Sparkle's weekly book shipment arrives one book too big. Among the others, there's a handbook about pony genetics. Curiosity leads her to an interesting discovery.

Sequel here