The film, which stars Dirk Bogarde and features Marius Goring, David Oxley, and Cyril Cusack, is based on the 1950 book Ill Met by Moonlight: The Abduction of General Kreipe by W. Stanley Moss, which is an account of events during the author's service on Crete during World War II as an agent of the Special Operations Executive (SOE).

The title is a quotation from Shakespeare's A Midsummer Night's Dream, and the book features the young agents' capture and evacuation of the German general Heinrich Kreipe.

Travelling mainly by night across mountainous territory, the group has to evade surveillance by German search parties looking for the General, but is given assistance by townspeople and other resistance partisans.

After a final push to reach a secluded cove on the far side of the island where they are to be picked up by the Royal Navy, the group finds the area occupied by German troops.

Kreipe offers Niko, a young boy travelling with the group, a gold coin, telling him that if he goes down to the beach, he will get a pair of German jackboots.

[7] In Million Dollar Movie (1992), the second volume of Michael Powell's memoirs, he describes Ill Met by Moonlight as one of The Archers' "greatest failures,"[8] despite the film's financial success.

Part of his unhappiness is attributed to Pressburger's screenplay, but he also describes conflicts with Rank's studio bosses over casting, film format, and locations.