Johnny Rico gets exiled to Mars to whip a battalion of recruits who don't believe the war is real. The bugs don't care what they believe. What starts as a training montage becomes a brutal lesson in the cost of apathy, and by the time the hive makes contact, Rico's worst recruits are the only soldiers who understand what it means to die for something you stopped caring about yesterday. The movie trades character arcs for a single, punishing idea: complacency is the real enemy, and the bugs are just the clock running out.

Following the events of Invasion, Johnny Rico has been demoted to colonel and sent to a satellite of Mars to train fresh recruits for the Federation. These Martian troopers perform poorly and treat the bug war lightly, since their home world has been untouched by the fighting. Across Mars, support for the war is weak, and some even call for leaving it. That relaxed attitude leaves the planet unprepared when the bugs strike. Meanwhile, Sky Marshall Amy Snapp quietly pursues her own plans for power, with no one aware of her scheme.