Amadeus’s son Nick (Matt Dillon) decides his father should move in with him and his family. But tensions are high between Nick and his overworked wife, Sarah (Emily Mortimer), and the old man’s presence just makes things worse. He pees in the fridge, leaves a cooked chicken in the closet and spends evenings calling his dead wife on a banana he thinks is a phone. That is, when he’s not chainsawing the garden, accidentally firing off loaded guns around his 10-year-old granddaughter, Tilda (Sophia Lane Nolte), or setting fire to the kitchen.

To go with its bizarre plotting and shrill performances, the film seems to have been edited in a Cuisinart. But those are the least of its crimes. Amazingly, nobody seems worried about leaving Tilda unattended with Amadeus. Instead, the movie treats this as an opportunity for the precocious girl to have bonding adventures with her kooky grandpa. The director, Til Schweiger (remaking his financially successful 2014 German film), and his collaborators clearly understand the devastating toll of this disease, which makes the decision to turn Amadeus’s antics into comic set pieces that much more disheartening.