The Big Six is the ninth book of Arthur Ransome's Swallows and Amazons series, published in 1940. The book returns Dick Callum and Dorothea Callum to the Norfolk Broads where they renew their friendship with the members of the Coot Club. It is set in September 1931 (plus the last chapter takes place on a Saturday morning in late February 1932). The book becomes a detective story as the Ds and the Coot Club try to unravel a mystery that threatens the Death and Glories freedom to sail the river.