1969. Hollywood descends on a tiny Scottish village for the making of Billy Wilder's most ambitious picture yet: a sprawling epic detailing The Private Life of Sherlock Holmes.
But the formidable director and his crew soon come into conflict with Jim Outhwaite, a young scientist seeking evidence for monsters. 2014. Stuck just a short walk from the East London street where she grew up, ambitious Film Studies lecturer Gemma MacDonald is restless and hungry for change.
A job offer in the Highlands seems to offer escape - but only at a cost to her relationships with family and an equally ambitious American boyfriend.
Then a lost print of Gemma's favourite film turns up, and with it, an idea... Two stories, separated by 45 years, are set on collision course - on the surface of Loch Ness, under the shadow of a castle - by the reappearance of the continuity girl herself: April Bloom.