In a world where it takes two years for a new series of Sherlock to come along, any extra material featuring the detective and his friend John Watson is gold dust.
Which means fans are likely to be downloading the new Sherlock app in their droves…
Sherlock: The Network features exclusive video footage of the show's stars in character, shot during snatched moments on the set of Sherlock series three.
There’s an introduction in which Benedict Cumberbatch's detective enlists you in his Homeless Network (before insulting your personal hygiene and implying you’re an idiot, obviously). There are appearances too from Mark Gatiss as Sherlock's sardonic brother Mycroft, while Louise Brealey’s lab geek Molly Hooper also chips in.
And at the heart of the adventures there’s Martin Freeman as John Watson, texting you, leaving you voicemails and even taking you back to his Baker Street rooms (yes, fangirls, it’s a lot like that dream you had last night.)
Whether or not there’s an appearance from Andrew Scott’s newly resurrected villain Moriarty, the app’s creators Project Factory refuse to confirm or deny.
But either way, for Sherlock obsessives The Network has the goods.
Luckily, it's also a neat, enjoyable little app that will keep you entertained even if you're not the sort of person who regularly finds themselves daydreaming about Moriarty and Sherlock's rooftop kiss.
There are ten cases to tackle, centred around a map of London and consisting of a series of puzzles to solve. There are clues, items and cash to collect, and each mystery is interspersed with contact from the characters.
Speed means points, and since there’s a global leaderboard, you may well find yourself going back to cases multiple times in an attempt to complete them more quickly.
In terms of the puzzles, think a slightly less taxing (and far less wide-ranging) version of the Professor Layton mysteries on the Nintendo DS.
Each time you take the tube (the most cost-effective way of getting around Sherlock’s London) you have to shift pieces of track around a grid, against the clock, in order to reach your destination as fast as possible. You’re also challenged to unscramble audio tracks, crack codes and break into password-protected email accounts. You even get to poke around Sherlock’s Baker Street sitting room in search of clues.
Then it’s off to your Mind Palace to put the pieces of the puzzle together, sifting the three key clues from an assortment of whirling words and phrases. Job done and on to the next case.
But if you’re waiting for a thank you from Sherlock, don’t hold your breath…
Sherlock: The Network is available for iPhone and iPad and is available to download from the App Store now, priced £2.99