Rent Spider's Web (1982)

Clarissa Hailsham-Brown (Penelope Keith), wife of a Foreign Office diplomat, is inconvenienced by finding a corpse in her drawing-room. Expecting her husband home with an important foreign politician, the only thing to do is hide the body and persuade her three house guests to become accessories and accomplices. To complicate matters, as Clarissa starts her search for the motive and murderer, she must convince a police inspector who has shown up, that there is no murder at all.