Returning from a combat mission in a retrieval ship, the Zephyr, the Roughnecks are re-routed to an asteroid to join scientists from another ship, the Sequoia, in a quest for a bio-weapon against the bugs. Just as they are coming in for a landing, tiny flame-breathing bugs, Firefries, hatch from Zander's skin. The ship crashes, badly damaged, but there are no serious injuries. Teams are sent out to locate the Sequoia. One team, Razak and Doc, falls into a subterranean network where they are attacked by marshmallow-like Leeches. Another team, Brutto and T'Phai, find themselves in a battle with adult, human-sized Firefries. Razak and Doc, joined by Dizzy and Gossard from the ship, join in this battle. Meanwhile, the third team, Carmen and Rico, is buried by an avalanche, and beneath the snow they share some intimate moments. Dizzy saves them. All return to the Zephyr, where Higgins awaits with the recovering Zander. They finally realize that they're on the wrong asteroid; the Sequoia awa

The Zephyr remains crash-landed on a frozen asteroid. A team is sent out to collect Toxin B-3, a potent bio-weapon that they've found here, while Gossard and others remain at the ship to try to get the communications system working to send an SOS... and to protect the ship from Firefries.

Having crashed on a barren asteroid, the Roughnecks try to make their way to a crashed science vessel for help.

The Zephyr is still stuck on the ice asteroid. The Roughnecks are running low on ammunition and the Fireflies keep attacking. Gossard suggests they use the Toxin they've collected to set up a poison gas perimeter. To give him time T'Phai, Flores and Rico lead the Fireflies off as human bait. Things go wrong though and they are trapped with no apparent way out. Suddenly Zander appears and does a Pied Piper act with the Bugs - they all seem to fall into a giant crater. The team return to the ship and their report convinces every one Sander has bought the farm - but he suddenly reappears even crazier then before. Razak boots Rico up to a Corporal during the next battle session during which an tremor send the Zephyr into another crater. The ship eventually lands in a lake of corrosive liquid and is running low on air. Doc and Brutto go looking for an oxygen supply. T hey manage to find one but barely make it back to the ship. Doc though has other news! He is

The Zephyr is trapped inside a giant Bug. Razak sends out a team to try and retrieve oxygen from the location found by Doc and Brutto.