Danny Collins is a rocker of the old school, of those who lived in the seventies with all that this entails in the way of life. Despite all the time that has happened, and that Danny is already an old man, his type of life has not changed much and therefore the excesses continue to predominate.
Suddenly that lifestyle changes radically. This time it is not a health problem that makes you change your life, but a letter from John Lennon written forty years ago and never delivered.
The letter was addressed to Danny and his manager just handed it to him. When he reads something he makes a turn to his life, so that begins a rapprochement with his family, which he has not seen for a long time.
He will also try to find love once and for all, in what seems like a second part in his life, a second better part.