In the 1970s legendary rock musician Danny Collins (Al Pacino Al Pacino) experienced a low ebb in his life when his agent (Christopher Plummer Christopher Plummer) found a letter that had never been delivered in 40 years. The letter actually came from Beatles lead singer John Lennon, who wrote to him at the age of 19 40 years ago, which inspired him again and resolutely left his current luxury life. He embarked on a journey to find the meaning of life, during which he gained true love and creative inspiration that had disappeared for a long time.