Firefly: Carnival is the 6th book in the series, but chronologically it would be first because the events in it occur during the time of the original TV series. That makes it a pretty standalone novel with a unique setting for telling a fun story because the planet Bethel has a definite Las Vegas vibe going for it. On Bethel, Carnival is approaching and that means three days of non-stop partying, but that's not the reason why the crew of Serenity have arrived there. Mal and crew have taken on a security job that requires them to guard an important shipment of minerals, which should be a piece of cake. Of course, even when Mal is trying to be on the right side of the law, things don't go according to plan. The shipment is stolen and the crew of Serenity finds themselves split up, with two of them taken hostage by the owner of the lost shipment. If Mal doesn't come up with the 500 platinum required to pay for the shipment, then those two will be executed, and local law enforcement won't do anything about it. This puts the rest of the crew at odds and it results in a lot of arguing over what the plan should be. When that fails to produce a viable option, multiple schemes are taken on by various crew members, each trying to earn some quick money before it is too late.
Firefly: Carnival - not so easy money
