Basically that among other things including werewolves, changelings, normal bat ponies, plots against Equestria, and the importance of "stranger danger". Also zombies. Drugs may or may not be involved with all of that.
After an infamous event, the city of Cloudsdale disappeared into the clouds. After over a year of ponies vanishing, including recon teams and one of his friends, a unicorn suddenly finds himself confronting the mysteries of the City in the Clouds.
A sequel to "All These Lights". Time Turner is connected to a series of events that are an immediate result to his actions before returning to Ponyville that Hearth's Warming Eve.