Hellfire Club Events are reoccurring in-game events where you get to play themed HFC stories, separate from the basic campaigns that are playable at any time. In these special HFC events you’ll also experience locked and timed areas, which means that new areas will unlock after a certain amount of time has passed. Each event will have a set amount of areas, visible on the main event page.
Hellfire Club Events are available after unlocking the Hellfire Club feature at Chapter 5, Mission 1. Check for more information and requirements in the Hellfire Club Event view.
Hellfire Club Events don't follow a set schedule, but you will find more information about them when they are live. Keep an eye out for further details in the in-game news! You can read more about the timed areas in the “What are the locked and timed areas and how do I access them?” FAQ.