The Big Six is the ninth book of Arthur Ransome's Swallows and Amazons series of children's books, published in 1940. The book returns Dick and Dorothea Callum, known as the Ds, to the Norfolk Broads where they renew their friendship with the members of the Coot Club. This book is more of a detective story as the Ds and Coot Club try to unravel a mystery that threatens the Death and Glories' freedom to sail the river. Dorothea names the group of amateur detectives "The Big Six", an allusion to the "Big Five" group of murder detectives at Scotland Yard. Source: Wikipedia (en)