When Muriel Carew attends a lavish society party, the last person she expects to bump into is her ex-fiancée Henry Jekyll, a man she's not seen for many years. When Jekyll turns out to be investigating a series of missing persons in London, Muriel is intrigued. But Jekyll is not working alone, and if Muriel wants to aid in the investigation, she must work with both Henry and his partner, the monstrous and uncouth Mr Hyde.

As their search takes a dark turn and a missing persons case becomes a murder investigation, Muriel finds herself deep in a mystery involving a nefarious group exploring their own hidden alter-egos within the beating heart of London's high society.

To solve the case and bring those responsible to justice, Muriel must find a way to place her trust in Mr Hyde, which might mean uncovering secrets about her own life she never dreamed of discovering.