A forgotten play by one of the world's best known murder mystery writers has come to light more than 70 years after it was written.
Christie's grandson Mathew Prichard (left) rooted out the play
Agatha Christie - the creator of fictional Belgian detective Hercule Poirot - penned several plays including the world's longest-running play, The Mousetrap.
But The Secret of Chimneys, a spy thriller Christie wrote in 1925, has lain forgotten in the vaults of the British Library and has only just been uncovered.
The play, a spy thriller set around European politics in the 1930s and based on Christie's book of the same name, is now set to premiere in October in Canada.
Mathew Prichard, Christie's only grandson, told BBC Radio 4's Today programme: "A producer in Calgary in Canada wrote us a letter saying he understood there was this unperformed play. We said we didn't know anything about it."
He asked The British Library, which is obliged to keep a copy of every play ever registered, to look for it.
"Sure enough, [it] turned up with a copy of Chimneys, " said Mr Prichard.
The play had certainly never been performed on the professional stage, he added.
Having read the play, Mr Prichard told Today: "I don't think it was forgotten with good reason, probably because it's not an ordinary Agatha Christie whodunnit.
Christie may have been "typecast" as a whodunnit playwright
"Once my grandmother began to write whodunnit plays like The Mousetrap and Witness of the Prosecution, those were the sort of plays that the public expected to see from her.
"Producers and impresarios expect a fairly staple diet - or did when my grandmother was alive. I think even if they had known of its existence they probably would still have gone on doing the whodunnits."
Mr Prichard praised his grandmother's skill and ability to entertain on the stage.
"I think she's underestimated as a playwright and I think this play may well confirm that," he said.
Chimneys, as it is now known, will premiere at the Vertigo Mystery Theatre in Calgary, Canada, in October.