In the latest edition of Witness, exactly four players participate as members of the secret "Witness Service" to fight crime and solve mysteries! In this cooperative campaign game with 8 interconnected cases, players first read an introductory prologue and then are given separate sets of clues to examine and memorize.

A case unfolds over four rounds, where a pair of players will be directed to whisper the facts they know to a specific person, except for any details they have learned from previous rounds. After storing all the information in memory for four rounds, players will have the opportunity to jot down notes on what they remember before secretly answering three questions about the case. The team's final score is the total of all correct answers, with a maximum of 12.

Witness is filled with tension and laughter as the best agents of the Witness Service try to keep their clues straight while chasing the truth.

The Sigma Club contains an adventure with 8 individual cases that interconnect into an overall story: A university in Lugano, Switzerland, is suspected of being involved in criminal activities. When a student is murdered, investigations lead the players to Italy. Apparently, the Mafia is involved. And then, suddenly, events take a turn for the worse…