The mythology-rooted “Percy Jackson & the Olympians” franchise is fairly engaging stuff, unabashed “Harry Potter” knockoff or no. Author Rick Riordan’s popular kid-lit series made its screen debut three years ago with an adaptation of “The Lightning Thief” — directed by “Potter” alum Chris Columbus, naturally — and proved to be a fun, brisk, even intermittently educational fantasy spectacle. As the lead, Logan Lerman (“The Perks of Being a Wallflower”) skated through the action with easy charisma. If the movie had had a convincing emotional core, the imitation discussion might have been footnote material.
The new sequel, “Percy Jackson: Sea of Monsters,” delivers more of the same, on all counts. Dispensing with any rote civilian-world angst, the movie dives right into the latest challenge facing hoodied demigod Percy: An assault on Hogwarts — er, Camp Half-Blood — has fatally damaged a mystical tree that projects a protective barrier around the compound. Percy and his demigoddess gal pal, Annabeth (Alexandra Daddario), realize that the healing power of the legendary Golden Fleece is the answer.