Ben Platt, as the titular hypersensitive teen, artfully carries the show in the debut musical scored by La La Land’s Benj Pasek and Justin Paul. Emotionally authentic strings-and-guitar-propelled songs—particularly the out-of-control Act 1 finale, “You Will Be Found”—drive a story about loneliness that leads to an Internet-shaking misunderstanding. The soaring “For Forever” and righteous, rock-driven anger of Rachel Bay Jones (as Ben’s mother, in “Good for You”) help give this musical the emotional heft of a great pop album.