Fresh off the triumph of solving her first case, Enola Holmes (Millie Bobby Brown) follows in the footsteps of her famous brother, Sherlock (Henry Cavill), and opens her own agency - only to find that life as a female detective-for-hire isn't as easy as it seems. Resigned to accepting the cold realities of adulthood, she is about to close shop when a penniless matchstick girl offers Enola her first official job: to find her missing sister. But this case proves to be far more puzzling than expected, as Enola is thrown into a dangerous new world - from London's sinister factories and colorful music halls, to the highest echelons of society and 221B Baker Street itself. As the sparks of a deadly conspiracy ignite, Enola must call upon the help of friends - and Sherlock himself - to unravel her mystery. The game, it seems, has found its feet again.