Aging rock star (Al Pacino: Manglehorn) has a sad because he only just now learned that John Lennon had written him a letter in 1971 — it never got to him — and warned him about how it’s not fame and fortune but “only you” that can corrupt a musician’s art. And because Danny Collins never received this sage advice, he corrupted his art, and now is forced to spend his incredibly lavish and luxurious old age singing the same damn hit song over and over again to aging fans he disdains. (That song is “Hey Baby Doll,” which sounds so much almost exactly like “Sweet Caroline” that it could be part of a case study in the law books about copyright infringement.) But now the letter, finally in his possession, prompts a three-quarter-life crisis. “If I’m gonna find any kind of redemption,” Danny tells his manager (Christopher Plummer: Hector and the Search for Happiness), “I can’t waste any more time.” And so writer-director Dan Fogelman’s (Cars 2) utterly obvious and clichéd dramedy sets Danny on the road to superconvenient redemption. Fogelman mines “charm” from the celebrity fairy dust Danny’s leaves in his wake — look how he sets up those two cute young people working in the hotel! — and from the ministrations of a hotel manager (Annette Bening: Girl Most Likely) who takes no shit and gives no fucks, offering just the sort of tough love that a man of Danny’s age really shouldn’t need to get his act together. And when Danny connects with the grown son (Bobby Cannavale: Ant-Man) he’d never before met and his wife (Jennifer Garner: Alexander and the Terrible, Horrible, No Good, Very Bad Day) and little daughter (Giselle Eisenberg: Sex Tape), Fogelman feels the need to invent not one but two family crises for Danny to graciously step in and resolve. The very talented cast is very game, but there’s nary a word or an act here that is very convincing. Is that the world’s tiniest violin I can hear on playing on “Hey Baby Doll”?