The book opens with Schofield's ten-man Marine Recon team parachuting onto the deck of the soon-to-be-decommissioned aircraft carrier, USS Nimitz CVN-68, along with three other special forces squads - a Delta Force team, a squad of SEALs and a force from the 82nd Airborne Division. The Delta team make landfall on the island while the other three teams investigate the aircraft carrier.
It quickly becomes clear that the island was the testing ground for an elite force of supersoldier, as the Airborne and SEAL teams are quickly slaughtered. A DARPA scientist, whom Schofield's team stumble across, explain that the enemy is a group of genetically and electronically enhanced gorillas, armed with modified M-4 Colt Commandos and extremely deadly in melee combat.
The few remaining Marines dispatch significant numbers of the gorillas in a large battle on board the carrier, eventually departing to investigate the island. Schofield comments that the island is home to an extensive tunnel network dating from World War II, which features an uncommon self-destruct mechanism: sea doors which can flood the lower parts of the tunnel system in the event of an enemy force capturing the base. Schofield then realises the gorillas are somehow controlled by Captain William Buck "Buccaneer" Broyles, the former leader of what was acknowledged to be the best Marines Unit, due to the similar tactics his Marines and the gorillas employed.
They set a trap to lock the remaining force in an old ammunition storage bunker before detonating the munitions, but the Delta team's entrance with the rest of the DARPA team (who deactivate the gorillas' neural chips) changes the situation. What is controlling (or at least, calming the apes down) is a silver disc, which are on the men testing Captain Schofield and his group, including the Delta force.
Dr Knox, the scientist in charge of the project, tells Schofield that they are the sole survivors of a field test for the apes, which has so far killed five hundred Marines and two special forces squads. He congratulates Schofield on his success, before instructing the Delta team leader to execute them. However, Mother jams the radio signals controlling the apes (remember the silver discs...) releasing them to murder their creators, the scientists. The Delta team is distracted and Schofield's team fires upon them and kills them, leaving only Broyles. Schofield opens a sea door, flooding the tunnels and drowning the gorillas along with the "Buccaneer". They leave on a C-17 which was sent to pick up the DARPA and Delta teams along with the apes.
- Captain Shane "Scarecrow" Schofield
- Gunnery Sergeant Gena "Mother" Newman
- Corporal Sean "Astro" Miller
- Sergeant Paulo "Pancho" Sanchez
- Corporal Harold "Hulk" Hogan
- Malcolm Knox
- Zak Pennebaker
- Captain William "the Buccaneer / Buck" Broyles
- Delta Leader Hugh "Flash" Gordon
- Eastern Gorilla (G. b. beringei)
- Project Stormtrooper Gorilla