Here's an idea for a Broadway musical: An awkward boy with an absent father and an overwhelmed mother gets involved with friends in a dubious scheme that spins out of control and almost undoes him. Is it 'Dear Evan Hansen'? If only. Alas, 'The Lightning Thief: The Percy Jackson Musical' is a pale patch on the earlier show and a failed attempt to board the teenage fantasy-angst train. (See also: 'Be More Chill' and, more successfully, 'Harry Potter and the Cursed Child.') Based on the popular 2005 novel by Rick Riordan, it is both overblown and underproduced, filled with sentiments it can't support and effects it can't pull off.