WHY BOTHER TO KNOCK

Bill Ferguson, a travel agent in Edinburgh, has an argument with his girlfriend Stella after he loses the key to his apartment. Unnoticed by Bill, Maggie, an American business associate of his, finds his key in his trouser cuff where he had dropped it, but, before returning it, she makes a copy of the key and gives Bill a gift of a case containing several copies of the key with his address on an attached metal tag.

Subsequently travelling around Europe on a business trip, Bill has romantic encounters with three women, giving each one a standing invitation to visit him when in Edinburgh plus one of the keys to his flat. When two of them, plus the daughter of the other, arrive at about the same time to attend the Edinburgh Festival, they all decide to stay with Bill, and Bill has to cope with the women all meeting each other, as well as Stella finding out about them.

Bill faces the consequences when the women he invited, plus Stella, all converge at his flat, leading to confrontations and comedic chaos.

The ending brings all of Bill's romantic entanglements into the open, forcing him to deal with the fallout of his carefree invitations and the prank with the keys. It's a classic farce resolution: misunderstandings pile up before everything comes to a head, highlighting the perils of juggling too many secrets—and too many guests—at once.