Enola Holmes is still on the run from her brother and world's most famous detective Sherlock Holmes. After one close encounter too many with him, Enola must abandon her disguise and find a new way to avoid discovery.

But when Sherlock's right-hand man, Dr Watson, goes missing without a trace, Enola is unable to resist investigating. Especially when she learns that a bizarre bouquet - with flowers that all symbolise death - has been delivered to the Watson residence.