If you'd like to take part, join the Cult of Chaos, Chaosium’s volunteer network of gamemasters.- it's free! More details about the campaign at the Flotsam & Jetsam FAQ.
Flotsam and Jetsam is presented as four separate and loosely linked scenarios, released on a monthly basis. Each part is essentially stand-alone, offering one or more sessions of play. They do not require the same players to take part, although returning players will, of course, enjoy a deeper level of fun by the fact they are engaging with a wider story.