Paul McCartney had a happy, well-adjusted family until his mother died, throwing his life into a dark alternate universe. In this alternate universe, he joined a band, had insane talent, and wound up the most famous musician on Earth. But then his band began to die too, and he reached out to the memory of his mother for help to get through it.

I have a good mother, and she has always been very talented at giving me little phrases to say when I am worried about something. It virtually saved my childhood. And sounds like Paul's mom was good at that too.