When Libby Nicholls arrives in London, the first person she meets on the bus is elderly Frank. He tells her about the time in 1962 that he met a girl on the number 88 bus with beautiful red hair just like her. They made plans for a date at the National Gallery art museum, but Frank lost the bus ticket with her number on it. For the past sixty years, he's ridden the same bus trying to find her, but with no luck. Libby is inspired to action, but with Frank's dementia progressing quickly, their chance of finding the girl is slipping away. Their quest shows Libby how important it is to embrace her own chances for happiness before it's too late.