Questions of identity, love and loyalty are at the heart of writer/director Sean Durkin's haunting mystery drama. Martha (Elizabeth Olsen) contacts older sister Lucy (Sarah Paulson) out of the blue and comes to stay with her and posh British husband (Hugh Dancy) in their luxury lakehouse, but seems strangely unable to cope with normal life. That's because she has just escaped after two years with a cult, where charismatic leader John Hawkes named her Marcy May. But will he let her go that easily? Durkin cuts frequently between the two timeframes, using different visuals to juxtapose the hazy, slow-paced cult life with Lucy's wealthy but austere world. Olsen is simply mesmerising, perfectly capturing the brainwashed Martha's disorientation and conflicting emotions: equal parts needy and hostile, she's desperate for love, but unsure whether she's deserving of it. The rest of the cast is equally impressive, in particular Hawkes as the manipulative, Svengali-like cult leader. Durkin's intelligent, hypnotic and compelling film echoes Martha's fractured mental state, so as the events of the past are slowly revealed, we're never sure whether they are real or imagined. But they are certainly sinister and unsettling, and will linger long in the mind.