An elderly couple, Norman and Ethel Thayer, spend their summers at their lakeside cottage in New England. Norman is a curmudgeon with a failing memory, while Ethel is energetic and nurturing. This summer, their estranged daughter Chelsea visits with her new boyfriend, Bill, and his teenage son, Billy. Chelsea hopes to repair her strained relationship with her father and introduces him to Bill and Billy with cautious optimism.

Chelsea and Bill leave Billy with Norman and Ethel for a month while they go to Europe, giving Norman and Billy an unusual chance to bond despite initial tensions. The couple's routines and the natural beauty of the lake provide a serene backdrop for evolving relationships and personal growth. Through fishing trips and shared experiences, Norman and Billy gradually develop a sincere connection. As the summer progresses, the family members confront past grievances and seek reconciliation, witnessing both the frailty and resilience of life.