Mars is under siege! Just before Halloween 2071, a terrorist bomb destroys a tanker truck on Highway One, close to a densely populated crater city. There are casualties up to half a mile from the blast. 500 killed or injured by what appears to be a biochemical weapon. The rewards for the bombers capture is massive and there are four humans and a dog who really need the money. Down on their luck as usual, the crew of the Bebop get on the case.