Series three is over and Sherlock will have no new mysteries to solve for many months. However, fans suffering from severe Cumberbatch withdrawal are about to get their fix with the launch of an official Sherlock app on Monday 20 January.

Created by digital production company the Project Factory, Sherlock: The Network is a game in which players become part of the detective's trusty "Homeless Network", assisting Sherlock and John in the cracking of 10 new cases. Whether "it was Derren Brown" is a valid solution remains to be seen, but the app promises new and exclusive footage of Cumberbatch and Freeman in character, who help out with a series of texts, voicemails and video calls.

Users must also navigate London via tube and taxi to collect clues, as well as contributing at least three new Reichenbach Fall theories to the Empty Hearse fan club. That last bit is not true, but of course, you will have already deduced as much.

Sherlock's executive producer, Sue Vertue, explained the decision to allow the game. "Sherlock fans have been asking us for ages to create an app and we think that through Sherlock: The Network, the Project Factory has created an impressive, innovative way for them to immerse themselves in a bit of Sherlock's world while waiting for us to make more shows."

The app will cost £2.99 and is available on the App Store from Monday.