The character tokens, the covered manhole tiles, the lit gaslight tiles are set on the board as shown in picture 1. The gaslights are lit when a lit gaslight tile is placed on them. They illuminate all the adjacent street hexes. If there is no lit gaslight tile on the hex, then the gaslight is out. John Watson: Move 1 to 3 spaces then choose his final direction. All characters on the line (except Watson) are visible. All characters are placed suspect side up on the board, along with manholes, lit gaslights and police cordons.

The character tokens, the covered manhole tiles, and the lit gaslight tiles are set on the board in accordance with the following picture. In this case, those characters who can be seen are innocent. The Detective flips them over to their Innocent side, without changing their location. The Witness card remains as it is until the next call for witnesses.

The Detective flips them over to their "Innocent" side, without changing their location. The Witness card remains as it is until the next call for witnesses. Those two characters are considered as seen since they are close enough to see each other in spite of the shadows. Reminder: note that this is only possible during a turn when the Witness card's Not Seen side is face up. Seen characters: the characters that are on an illuminated street hex (hex adjoining a lit gaslight) are seen, since they can be seen by anyone in the district, any passer-by. The same rule applies if two characters are on adjoining hexes, even in the darkness.

To use a character, a player can either move the corresponding character token or use the character’s special ability. The character card is then placed face down on the table.After that, some gaslights maybe shut off. Remove the lit token equal to the round number from the game. When a character is on (or moves through) an open manhole, he/she can use 1 movement point to go to any other hex with an open manhole.