The Fifth Estate conducts a comprehensive inquiry into the 13 hours of mayhem that constitute one of Canada's deadliest events. We hear from families of many of the 22 victims, and the terrible final moments their loved ones faced. Many questions remain about how the RCMP responded to the situation, and whether enough was done to protect the community. In one case, we show the RCMP was told of the presence of the shooter in a police cruiser hours before they acknowledged knowing this information. The piece explores the red flags police knew about with respect to the shooter, and presents a critical analysis of what went wrong on that April weekend.