Murder Ahoy! is a 1964 British film directed by George Pollock, based on elements from Agatha Christie's 1952 novel They Do It With Mirrors on a mostly original screenplay adaptation by David Pursall and Jack Seddon with Margaret Rutherford returning as Miss Jane Marple from the previous three films; Murder, She Said (1961), Murder at the Gallop (1963), Murder Most Foul (1964), along with Charles 'Bud' Tingwell as (Chief) Inspector Craddock and Stringer Davis (Rutherford's husband) as Mr. Stringer. It was produced by Metro-Goldwyn-Mayer and the film score was by Ron Goodwin. Location shots included Denham Village and St Mawes, Cornwall.

Unlike the previous three films that were adapted from Christie novels – The 4.50 from Paddington (Murder, She Said – the only Miss Marple novel used), After the Funeral (a Poirot mystery, adapted for Miss Marple with the title Murder at the Gallop) and Mrs. McGinty's Dead (another Poirot novel, adapted as Murder Most Foul) – this film used an original screenplay that was not based on any of Christie's stories.

It does, however, employ elements of the 1952 Miss Marple story They Do It With Mirrors. Specifically, the Battledore is a training ship for teenage boys with criminal tendencies, who are supposedly being set on the straight and narrow path – when, in fact, one of the members of the crew is training them for careers in housebreaking. Likewise, in They Do It With Mirrors, a boarding school for delinquent youths is actually being used to hone their criminal skills. This is the only element in the film borrowed from a Christie story.