Sheltering beneath the streets of London, the company of a West End play find themselves isolated from their loved ones when a nearby terrorist attack cuts short their final night performance. Minds racing over past anxieties from the run, they contemplate life-and-death decisions within the claustrophobic confines of the theatre basement.

Stuck in a relationship that is no longer fulfilling, buttoned-up office worker Alice begins to develop new desires, but her repression soon manifests as a dark presence that begins stalking her.