Bienvenue au club Monsieur Moutarde

This evening at the Penny Black, a private club in the heart of London, was set to be a success! Sir Bloch, its founder, was about to retire and had, for the occasion, gathered all his friends around him. Clearly, one of them had something to reproach him for... But who? It's up to you to shed light on this case by unmasking the culprit and discovering the weapon of the crime and its motive!