The story is told during three acts where the mystery unfolds live. There are actors but some of the guests are also turned into characters in the story. Obviously, one or more people are not going to make it through the night and your goal is to figure out who the murderer (or murderers) are. In between the acts you have time to do investigation and interact with each character to collect clues. Throughout the show you also get a three-course meal and can order drinks to help lubricate your brain.
The Murder Mystery Co. hosts a dinner every Sunday at the Old Spaghetti Factory in San Pedro Square. They have been performing in the Bay Area for the last 3+ years and have a very talented group of actors. There are different themes and stories, but it looks like the two that are alternating right now are "A Dance with Death" and "Midnight at the Masquerade." The also host a Thursday event in Redwood City at another OSF.
Fore more information and for tickets, head over here.