The Unexpected Guest is a novelization

Novelization

A novelization is a novel that is written based on some other media story form rather than as an original work.Novelizations of films usually add background material not found in the original work to flesh out the story, because novels are generally longer than screenplays...

 by Charles Osborne

Charles Osborne (music writer)

Charles Thomas Osborne, born 24 November 1927 in Brisbane, Australia, is a journalist, critic, poet and novelist, and a recognised authority on opera. He was assistant editor of The London Magazine from 1958 until 1966, literature director of the Arts Council of Great Britain from 1971 until 1986,...

 of the 1958 play of the same name

The Unexpected Guest (play)

The Unexpected Guest is a 1958 play by crime writer Agatha Christie.The play opened in the West End at the Duchess Theatre on 12 August 1958 after a previous try-out at the Bristol Hippodrome. It was directed by Hubert Gregg.-Plot summary :...

 by crime fiction

Crime fiction

Crime fiction is the literary genre that fictionalizes crimes, their detection, criminals and their motives. It is usually distinguished from mainstream fiction and other genres such as science fiction or historical fiction, but boundaries can be, and indeed are, blurred...

 writer Agatha Christie

Agatha Christie

Dame Agatha Christie DBE was a British crime writer of novels, short stories, and plays. She also wrote romances under the name Mary Westmacott, but she is best remembered for her 66 detective novels and 14 short story collections , and her successful West End plays.According to...

 and was first published in the UK by HarperCollins

HarperCollins

HarperCollins is a publishing company owned by News Corporation. It is the combination of the publishers William Collins, Sons and Co Ltd, a British company, and Harper & Row, an American company, itself the result of an earlier merger of Harper & Brothers and Row, Peterson & Company. The worldwide...

 on September 6, 1999

1999 in literature

The year 1999 in literature involved some significant events and new books.-Events:*June 19 - Stephen King is hit by a Dodge van while taking a walk. He spends the next three weeks hospitalized...

, and on October 1, 1999 in the US by St. Martin's Press

St. Martin's Press

St. Martin's Press is a book publisher headquartered in the Flatiron Building in New York City. Currently, St. Martin's Press is one of the United States' largest publishers, bringing to the public some 700 titles a year under eight imprints, which include St. Martin's Press , St...

.

The book was written following the successful publication of the novelisation of the 1930 play Black Coffee in the previous year. Like that book, the novelisation is a straightforward transfer of the stage lines and directions of Christie's script into a written narrative. Osborne chose not to add characters, lines or scenes which would alter in any substantial way what had been presented on the stage forty-one years earlier although minor amendments were made to produce suitable chapter endings.

The following year, Spider's Web underwent a similar novelization process, again by Osborne.

Plot

On a foggy night, a man called Michael Starkwedder breaks down near an isolated house and, entering it, finds the body of a dead man slumped in a chair. A woman stands over the corpse, gun in hand, and confesses to the murder but it is clear that she is covering up for someone else.