The film begins with Lewis (Luke Evans), a seemingly mild-mannered man who kidnaps Cathy (Kelly Reilly), a woman with a hidden past, and imprisons her in a small, windowless 10x10 room.

As Cathy struggles to come to terms with her captivity, she begins to discover more about Lewis’s traumatic past, including the loss of a loved one that might explain his motivations.

The film unfolds in the confined space of the room, where Cathy uses her resourcefulness to survive and attempt to manipulate Lewis into revealing more.

The tension escalates as Cathy eventually confesses a part of her past, revealing that she is connected to Lewis’s trauma in an unexpected way.

The film culminates in a dramatic showdown, leaving both characters' fates uncertain and challenging the viewer’s perceptions of morality, justice, and revenge.