In the 46th play by the prolific British playwright known for his ingenious plot twists, the "communicating" door between two adjoining hotel rooms is no ordinary portal. This one allows time travel and an opportunity to change events in the past. A professional dominatrix is called to the posh London suite of of a client, only to learn he only wants her to witness his confession to having hired a business colleague to murder his two wives. Unfortunately, the killer is also there, and the woman flees through a door she believes leads to the next room. Instead, she finds that it's 20 years earlier, and as she's transported back and forth through time, she tries to find a way to prevent the deaths from happening.