Meet up with your guide, who will brief you on the instructions for the game. Your guide will need to be in touch with you throughout, so you must bring a fully-charged mobile phone with internet access. You will also have to pay a £20 deposit for the rental of the spy kit. The deposit will be fully refunded to you at the end once you return the kit undamaged. The kit comes in a backpack that has all the clues and tools you need to work through the game including a 19th-century map of Edinburgh that is yours to keep. Once the game begins, you'll follow a series of numbered clues. Every clue is meant to be used in a particular location in the city and puzzles are solved by making use of permanent features in the city. No extra clues or hints are hidden around. The game unravels the story of Arthur Conan Doyle's most famous creation. Cover a good portion of Edinburgh and pass by some of the main landmarks: St Andrews Square, Princess Street and some other wonderful places off the tourist trail. Most of the game's locations have a connection to Sherlock Holmes' creator, Arthur Conan Doyle. You will finish by dropping the kit off and collecting your souvenir badge at the Arthur Conan Doyle centre, which is a 15-minute walk from the West End of Princess Street.  The duration of the game varies depending on the group, it could take anything between 2 and 4 hours, but the average group usually takes 2.5 hours if they don't take a break.