This is Will Hay's first Ealing film and it finds him in his usual role as a schoolmaster, who joins the staff of a school evacuated to a remote Scottish castle on the Isle of Skye during wartime, emerging from a blissful retirement to teach for victory.

As Hay had left Gainsborough for the new venture at Ealing it was apparent that he was making a clean break away from his old partnerships. Out went the writing team of Val Guest, Joe Orton & Marriot Edgar along with the comic partnership with Graham Moffatt & Moore Marriott and in came the writers John Dighton and Angus McPhail with actors Charles Hawtry and Claude Hulbert. The only retainer was Will's good friend the director Marcel Varnel.

Although Hay had played roles at Gainsborough that touched on the teaching theme, such as his headmaster mistaken for a prison Governor in Convict 99, this was the first time he had played the schoolmaster role since Good Morning Boys in 1937.

The plot of the film evolves around the strange goings on at the Castle. Hay is introduced to the castles caretaker who is played by John Laurie (Fraser from Dad's Army). He at any given opportunity recounts his fearsome story of the castles ancient curse and the tale of the phantom bagpipes.

A series of poisonings occur and the headmaster & his deputy are killed off. Hay with help from his boys set about to establish who the murderer is. They discover a secret chamber from where the sound of the phantom pipes is coming, which according to the castles legend are played when a death is imminent. It turns out that the pipes are being played from a gramophone record and our gangs suspicions are aroused. They are then trapped in this secret chamber by the castles matron who turns out to be a nazi spy and is responsible for the murders. She is using the location of the remote castle to signal to German U boats. Hay manages to escape the chamber and overcomes the matron whilst she is trying to send out a signal and all ends well.

At the very end of the film the phantom pipes are heard again and we see Hay looking rather worried. The pipes then turn into a drone (akin to a air-raid siren) 'Ah, it's the all clear!' announces Hay, and in a very unusual move for Hay, he then addresses the cinema audience and he quips 'Well you can go home now if you like, come on Claude!' (Claude being Claude Hulbert who played the part of the schoolmaster Mr Hilary Tisdaile.)