When Lauren returns home to her flat in London late one night, she is greeted at the door by her husband, Michael. There's only one problem—she's not married. She's never seen this man before in her life. But according to her friends, her much-improved decor, and the photos on her phone, they've been together for years.

As Lauren tries to puzzle out how she could be married to someone she can't remember meeting, Michael goes to the attic to change a lightbulb and abruptly disappears. In his place, a new man emerges, and a new, slightly altered life re-forms around her. Realizing that her attic is creating an infinite supply of husbands, Lauren confronts the question: If swapping lives is as easy as changing a lightbulb, how do you know you've taken the right path? When do you stop trying to do better and start actually living?