After the events of
Invasion, Johnny Rico has been demoted to the rank of colonel and relocated to a space station orbiting
Mars to train a new batch of troopers. Unfortunately, his squad is incompetent. Mars has low support for the war, seeing their planet unaffected by the bug conflict and even suggesting pulling out from the war. Because of their laid-back attitude, the denizens of Mars are unprepared for a full-scale bug invasion. Unknown to everyone, Sky Marshal Amy Snapp plans to destroy Mars while gaining popular support for doing it, having been aware of a bug nest growing under Mars for some time but deciding to take advantage of the bug attack to gain social and political support to scuttle the whole planet. She stages a fleet attack run on the Arachnid Quarantine Zone (AQZ) as a massive distraction. While the public is distracted, she plans to capture General Carl Jenkins, then fabricate a story in which the Federation was too distracted in the AQZ to save Mars and had to detonate a Q-Bomb (a planet destroyer whose power was demonstrated in the
third film) to cleanse the bug threat, thus blaming Jenkins for the loss of Mars. During the bug attack, Rico and his team survive the initial assault and manage to land on the Mars surface. While the bulk of the Federation start their attack run on the AQZ, Snapp captures Jenkins and disrupts all communications between Earth and Mars. However, before he was captured, Jenkins telepathically reached out to Carmen Ibanez to return to Mars. Meanwhile, during a bug attack, Rico's troopers are found by a rescue drop ship and everyone makes it on board except for Rico, whom the team presumes dead. When regaining consciousness, Rico sees his dead lover, Dizzy Flores, who died in the
first film, and who asks him to help stop the Q-Bomb. Unknown to Rico, Dizzy is a telepathic projection from Jenkins. While being beaten and drugged by Snapp, Jenkins manages to telepathically motivate Rico to help stop the Q-Bomb. Snapp then publicly announces the fall of Mars. Rico's surviving troopers realize he is alive and return to save him. Upon reuniting, the team heads towards the weather control tower to disarm the Q-Bomb. They overload the tower's systems to improvise a massive explosive device to thin out the enemy forces. With the Fed-Net back online, public reception of Snapp turns negative. Carmen arrives with a drop ship and rescues Rico's surviving team. Once evacuated, the tower's destruction destroys the bugs within its blast radius. In the aftermath, Jenkins breaks free from his captors and later returns to power. Rico is promoted back to the rank of general and leads the operation to reclaim Mars, while Snapp's treachery is revealed to the public. ==Cast==