The tone of Frank Vosper’s entertaining reworking of Agatha Christie’s stage adaptation of her short story Philomel Cottage is established in the sprightly opening exchange between Louise Garrard (Nicola Sanderson hamming it up in glorious Hyacinth Bucket style) and her niece’s friend Mavis Wilson (a solid Alice Haig) when the former accidentally breaks an ornate candlestick but covers up her misdemeanour by telling a porky pie.

The first of many lies, secrets and denials which pepper not the whodunit but what the programme notes describe as a “whodunwhat” plot directed by Lucy Bailey who brings the same vim and vigour to this co-production between Fiery Angel and Royal & Derngate Northampton as she brought to Witness For The Prosecution which continues to thrill audiences at London County Hall.

Another secret which is unearthed during the amusing opening are the second thoughts which said niece and bored secretary Cecily Harrington (Helen Bradbury in sparkling form) harbours about her “tepid romance” with her straitlaced fiancé Michael Lawrence (Justin Avoth as comically stiff as his Brycleemed hair and creased trousers). Second thoughts which are fuelled by the arrival of a boyish American with peroxide blonde hair Bruce Lovell (an excellent Sam Frenchum) who shifts from cute to psychotic at the drop of his little black book within which he records a string of cryptic notes.

Unlike Cecily’s “dull” and “monotonous” existence which runs like a Del Amitri song in that “nothing ever happens” and is described in withering terms as “hiding away in the cellar like a duff marriage present”, the action twists and turns to a gripping finale which challenges Bruce’s assertion that “a woman’s weakness is a man’s opportunity” and forces Cecily to reconsider her wish to “live before I’m grey and old – and dead”.

An enjoyable romp bolstered by a strong ensemble which includes Crispin Redman as the suave Dr Gribble, Molly Logan as the scene-stealing country bumpkin Ethel and Gareth Williams as the wily old gardener Hodgson; an edgy score by Richard Hammarton; atmospheric lighting by Oliver Fenwick; and a fine set by Mike Britton which like the titular stranger is both shifting and concealing.

Peter Callaghan