It's 1933 in pre-war London. Identical twin sisters Clara and Olivia Marionetta are rehearsing for their performance in the ballet Coppelia at the recently opened Sadler's Wells Theatre. Disciplined and dedicated, Olivia is the perfect ballerina- but no matter how hard she tries, she can't compete with Clara's rebellious charm. And now Clara has started a relationship with someone who Olivia secretly desires: passionate, bohemian Nathan, a pianist at the theater. Meanwhile, Olivia is unaware that she has cast a spell on another frequent visitor to Sadler's Wells- Samuel, a bashful ballet shoemaker apprentice, who steals into the building to catch a glimpse of her whenever he can. With rehearsals for Coppelia intensifying, both girls increasingly feel as though they are being watched. As infatuation turns to obsession and sinister secrets begin to emerge, all starts to unravel...