Man Overboard! is a detective novel by Freeman Wills Crofts, first published in 1936. It is the fifteenth novel in the Inspector French series. The book is set largely in Northern Ireland, and re-uses two of the characters from the earlier novel Sir John Magill's Last Journey (1930) which was set in the same country. As a MacGuffin, the novel centres on a supposedly newly discovered reversible chemical process that converts petrol into an inert form which is much safer for transport and storage.