The first film revolves around the titular character (Logan Lerman), who discovers that he is the son of Poseidon and that there are other kids like him who have similar mythological Greek backgrounds. It was sort of like "X-Men" but with Greek myths in place of comic book heroics. This movie has Percy and his buds trying to save the world from an insidious plot that has them venturing into the "Sea of Monsters" aka the "Bermuda Triangle."
And honestly, it does look kind of fun. Like the first film, it appears that the sequel will play around with the adult actors cast in very silly roles, like Stanley Tucci as Dionysus, Nathan Fillion as Hermes, and Sean Bean as Zeus. It looks like they are having an absolute blast, and it's possible audiences could, too. It's also worth noting that the screenplay was co-written by Scott Alexander and Larry Karaszewski, who wrote "Ed Wood," "The People Vs. Larry Flynt," and "Man in the Moon," and Marc Guggenheim, a beloved comic book author.