Thursday, June 2 at 9:00 p.m.

Enjoy a new spin on a familiar story in "Masterpiece Mystery!"

Returning home on a train from vacation, beautiful young socialite Iris Carr is befriended by an Englishwoman she knows only as "Miss Froy." When Iris falls asleep she awakens to find Miss Froy missing and her fellow passengers denying she ever existed. Is Iris going mad or did the encounter really take place?

It is 1931. Iris (Tuppence Middleton, "Inspector Lewis"), on holiday with friends in the Balkans, decides to escape her friends' raucous partying and travel home to London alone. After she faints on the platform of the railway station, she wakes in time to be rushed on to the train but with a pounding head and the feeling of being on the verge of a dream.

Finally seated, Iris is comforted by Miss Froy (Selina Cadell, "Doc Martin"), whose tweed suit and bookish looks belie a jovial and adventurous spirit. Comfort soon turns to horror when Miss Froy mysteriously disappears. With only the support of the infatuated young engineer Max Hare (Tom Hughes, "Silk"), Iris maintains the conviction that Miss Froy has somehow been abducted.

Other members of the cast include Keeley Hawes ("Upstairs Downstairs") as the cynical mistress of the ambitious Sir Peveril (Julian Rhind-Tutt, "Any Human Heart"), Danish actress Benedikte Hansen as the sinister Baroness, and Gemma Jones ("Duchess of Duke Street," "Bridget Jones' Diary") and Stephanie Cole ("Waiting for God," "Doc Martin") as spinsterly sisters yearning to get home to their garden.

Shown from left to right: Tuppence Middleton as Iris Carr and Tom Hughes as Max.