Tom Chadwick and his sister Bea find out from their father that a great-aunt, Victoria, has died. An old picture in the box of things that she's left for Tom sends him on a search, accompanied by his pal Pete, to discover the identity of the man in the photograph.

Tom learns that his great-grandfather, Harry Chadwick, was an actor and visits Hove, where he performed. He and Pete decide to run a kind of race in honour of Harry's famous comic act.

After discovering grandfather William was on the GB team in the cash-poor 1948 Olympics, Tom hears about his and Victoria's athletic feats from a close friend she bequeathed her flat to; he learns that William and Victoria had a brother, Brian. Bea and Monkey try performing. His great-great-grandfather Charles, Tom finds, was born in the USA.

Along with Bea, his father, and Luba, Tom visits his cousins in rural Derbyshire and learns why they have red hair. His American cousins in California invite him to visit.

Tom, Bea, and Pete drive to Barstow, where they find that great-great-grandmother Rebecca was not Native American, as Tom had thought.