When Libby Nicholls arrives in London, broken-hearted and with her life in tatters, the first person she meets on the bus is elderly pensioner Frank. He tells her about the time in 1962 he met a girl on the number 88 bus with beautiful red hair just like her own. They made plans for a date at the National Gallery, but Frank lost the ticket with her number written on it. For the past 60 years, he's ridden the same bus trying to find her. Libby is inspired by the story and, with the help of an unlikely companion, she makes it her mission to continue Frank's search.