‘Dear Evan Hansen,” the screen version of the acclaimed Broadway musical, draws its dramatic energy from the anguish of its young hero, a high-school senior who suffers from a severe anxiety disorder. Painfully lonely and terrified of the rejection that he constantly courts, Evan thinks in obsessive loops and speaks in apologetic whispers, though he sings ardently, sometimes beautifully, of his fears and yearnings. He’s played by Ben Platt, who began to develop the role in 2014, then went on to win a Tony for his brilliance on stage. You needn’t have seen the show—I did not—to understand how powerful his performance must have been. But the film suffers from a different condition, an emotional elephantiasis that is inexorable and ultimately terminal. What was by all accounts a modestly scaled production in all of its live-theater iterations has become a ponderous movie that turns earnest into maudlin, lyrical into lugubrious.

The title comes from an assignment Evan receives from his therapist—write letters to yourself in which you anticipate what will be good about each coming day. This isn’t easy for a social outcast, someone who’s been searching for himself without believing he has a self worth finding. Still, Evan writes them, and the letters might have been therapeutic except that one of them falls into the wrong hands.