After months of inactivity, Holmes and Watson have two cases thrust in their lap in a single day. First, a mysterious woman from Swansea, Wales, seeks Holmes' help finding her husband who has disappeared in the middle of the night. As soon as she leaves, Holmes receives word that there has been a prison riot with several dead and a few inmates missing. Lestrade is asking for his services.

Holmes believes the two cases are not a coincidence, but he has no idea who is behind it and to what end. They go to Swansea in what could be either a wild goose chase or a setup. Will Holmes unravel the mystery before they get to Swansea? If not what will be in store for them when they step off the train?