- Alastair Sim, George Cole, Terry-Thomas, Jill Adams, Raymond Huntley, Colin Gordon, Avril Angers, John Chandos and others
- Sidney Gilliat and Frank Launder
- Robert Day
- Frank Launder and Sidney Gilliat
Harry Hawkins is a mild-mannered watchmaker by day - but in reality the majority of his income comes from his longer-term work as a professional hitman for hire.
Specialising in bumping off those bloated and important figures - ambassadors, dictators, industrialists and the like - his latest client is a Middle Eastern group who wish Sir Gregory Upshott to be dispatched with before he can visit the region.
After inveigling his way into the affections of Upshott's middle-aged spinster secretary, the plan is arranged: but he had not bargained on a stray sheet of carbon paper arousing her suspicions and causing a visit to Hawkins's home address.
A further mix-up between his cleaner, a vacuum cleaner salesman named William Blake, and the newly-sold property next-door, leads to Blake and the house's new owner, Ann, seeing something they really shouldn't. Piecing two and two together, the pair eventually - and only just - make four, and head hot on the trail of Hawkins and Sir Gregory.
Events build up to a head at a small coastal hotel called The Green Man. With a grumpy hotelier, various couples conducting elicit rendezvous, and a trio of incompetent elderly musicians thrown into the mix, Ann and Blake's frantic search for Sir Gregory gets under way.