In the reimplementation of Witness, exactly four people fight crime together as members of the secret "Witness Agency" organization! A prologue introduces the case, after which each team member receives their own secret clues. In the four Whisper rounds, these are passed on to another person - in the direction of the arrow on the Whisper card. In the first round, only their own clues are whispered, from the next round onwards, the clues that the players received in the previous round are also whispered. After the fourth round of whispering, the players secretly answer three questions about the case. Those who have listened carefully and answered the questions correctly receive valuable points when the case is solved.

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