While it is not a main installment in the Scarecrow series, it is chronologically the fourth story to feature Schofield as the lead character.
A United States Marine, Lieutenant Rick "Razor" Haynes, is fleeing for his life through a soon-to-be-decommissioned aircraft carrier, the USS Nimitz, stationed on the dock of an old U.S. naval base known as Hell Island. Having watched his entire platoon of 300 Marines get slaughtered by an unknown enemy, Razor attempts to barricade himself, however he is caught off-guard and attacked, with his screams unheard as he is killed.
Some time later, Captain Shane Schofield and his ten-man Marine Recon team are HALO jumping onto the deck of the Nimitz, which had apparently been forced by a tsunami to dock at the base after collecting an unkown cargo, and now communications with the Nimitz and the base have been lost. Also doing a HALO with them are three other special forces squads - a Delta Force team, a squad of SEALs and a force from the 82nd Airborne Division. While the circumstances make it seem like this is all an exercise, Schofield and other members of his team are suspicious that such an exercise would include other specialised units since they would more likely trip over each other's toes, as well as the fact that they are carrying live ammunition.
The Delta leader, Hugh "Flash" Gordon, gives orders and reminds the other units of their objectives as his squad prepare to make landfall on the island itself (while the others are set to investigate the aircraft carrier). Schofield doesn't take kindly to Gordon attempting to exert his authority when they were all present at the briefing, and orders his team to switch to listening mode only.
As they move to investigate the control tower of the Nimitz, Schofield and Gunnery Sergeant Gena "Mother" Newman note the blood all around the deck in spite of the lack of bodies. As the other units call out their reports after landing, one of Schofield's men, Sergeant Paulo "Pancho" Sanchez, questions why Schofield isn't doing the same, and in response Schofield rebukes Sanchez by asking if he ever questioned his previous commander's decisions and tells him to focus on the mission.
The inside of the control tower is much the same as the deck; lots of blood and yet no bodies. Schofield notices an M-4 rifle on the ground that has been modified for a bigger index finger, while Mother reports that some of the blood spatter appears to be from limbs being ripped off instead of bullet impacts. The SEAL team leader, Gator, radios out to report that his team has investigated the main hanger and found a huge pile of hundreds of stacked severed hands (he repeats this horrifying fact by correctly guessing that some might believe they misheard this claim). Mother discovers a digital signal is being broadcast throughout the Nimitz, so Schofield asks her to use a radio spectrum analyser to tune in to the signal and be ready to jam it.
Suddenly the radio is filled with shouts and gunfire from the SEAL team as they come under attack from an unidentified enemy, and it becomes painfully clear that the SEALs have been eliminated when the radio goes silent. Sanchez makes to radio them to request any survivors to make contact, but Schofield orders him to remain radio-silent. As Pancho scowls, a loud animalistic roar is heard through the radio.
The Airborne Division team leader, Condor, does try to radio Gator and his men, and Mother realises that the signal has spiked in response to Condor's repeated calls. Using the ship's motion sensors, Schofield sees that a large number of contacts are moving in on Condor and his men, realising that their enemy is using their radio transmissions to track them. Unable to contact Condor to warn him without giving away their own position, Schofield reluctantly decides that the Airborne team will have to fend for themselves, and orders his team to head into the main hanger. Before he follows, Sanchez defies Schofield's order and contacts Condor's team on their private channel in order to warn them.
As they head towards the hanger, Mother reports that several of the enemy contacts have broken off from the main group and are heading towards their last location. As Schofield wonders how they could have learned their position, Condor makes one last report as he and his men are killed by the enemy. Sanchez attempts to convince Corporal Sean "Astro" Miller that the rumours of Schofield having gone off the deep end may in fact be true, and that this would never have happened if they were under the command of his previous unit's leader, Captain William "the Buccaneer" Broyles. Astro isn't interested in Sanchez's biased views, however, and the Marines find themselves in the main hanger.
The Marines move to investigate an observation platform, and are surprised to find a DARPA scientist, Zak Pennebaker, as he emerges from hiding to beg for their help. Pennebaker explains 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, to be used as a new type of frontline assault force. After the gorillas' combat skills were proven in a battle against a few Marine platoons, they apparently went rogue and began thinking for themselves, attacking the DARPA scientists and taking control of the island.
The Marines suddenly come under attack from the gorillas, and four of Schofield's team are taken out quickly and brutally, forcing Schofield to grab Pennebaker and order his team to retreat. Unfortunately, they realise they are being pushed towards a larger force of the gorillas, and so instead aim to head for the flight deck, commandeering of troop transport trucks to head up the ramp. Before they move out, Schofield is surprised to see Pennebaker rushing off on his own, but has no time to ponder the act before the gorillas attack.
During the pursuit, Schofield and Bigfoot get seperated from the others and are forced to ditch their truck off the flight deck, while Hulk is dragged down and killed by the gorillas. After their truck crashes on the flight deck, Mother, Sanchez and Astro are left exposed, but luckily Schofield and Bigfoot use the main gun of an abandoned F-14 Tomcat to cut down several of the gorillas. After ordering Mother's group to meet them at "Casper's door", the F-14 is shoved towards the edge by the gorillas, but the two Marines use the ejection seats to escape. Spotting a nearby CH-53E Super Stallion, Schofield hitches the chopper to one of the catapaults and lures dozens of the gorillas inside, then has Bigfoot launch the catapault so that the Super Stallion is launched overboard; Schofield jumps into the ocean at the last second while the trapped gorillas sink and drown.
Meeting the rest of his team at the submarine dock of the Nimitz (Casper's door) Schofield sits down to take stock of the situation. Sanchez misinterprets this as Schofield having a breakdown, and Mother berates him for his favoritism of Buck's unit despite it now being dismantled. Bigfoot, despite having also served in the Buck's unit, tries to assure Sanchez that Schofield is a good commander after having seen him defeat the gorillas. Sanchez goes on about how in the last war games they participated in, Schofield's unit drew a draw with Buck's by evading them until the games were over. As Mother points out that Schofield saw through the Buck's usual strategy, Schofield comes to a realisation; the Buck is here and in command of the gorillas.
The Buck is known for his tactic of having a small force drive the enemy towards a larger force, the gorillas attempted to do this to the Marines twice during the attack. Deducing the Buck is somewhere on the island itself, commanding the apes, and with Pennebaker's suspicious ditching of them, leading Schofield to conclude that this is in fact an exercise... for the gorillas and not the units that were sent to Hell Island. Schofield comments that his grandfather, Michael Schofield, who used to be a Marine during World War II, had operated on the island and shared stories with his grandson about the island's extensive tunnel network, 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.
With all this information, Schofield develops a plan to trap the remaining gorillas in an old ammunition storage bunker before detonating the munitions. Under the cover of night, the Marines sneak onto Hell Island and enter the tunnels, and in order to let the apes know where they are, Schofield radios Gordon to ask if he is still alive. The apes quickly move in, and when the last of the apes enters the ammunition storage chamber, the Marines pull back and prepare to open fire on the mountain of munition boxes the apes are standing on... when a voice calls out for them to stop.
Schofield's team hold their fire as the voice commands the gorillas to stand down, which they do. A few DARPA scientists (including Pennebaker), the Buck and Gordon and his Delta unit enter the chamber, and Dr Malcolm Knox, the scientist in charge of Project Stormtrooper, tells Schofield that they are the sole survivors of a field test for the apes, and congratulates him on his success. Schofield is disgusted that several American soldiers have died for this experiment, and Knox claims out that once the gorillas are used in the field the U.S. military won't have to worry about soldiers dying on the front lines anymore. Knox then tells Schofield that he and his people can leave, though before they move Schofield questions the Delta unit's role; Knox claims they were there to protect his team in case the units found out and turned on them.
As the Marines exit the chamber, Knox gives the Buck and Gordon a look that says that Schofield's team must be eliminated; the Delta unit holds the Marines at gunpoint, and the Buck is unmoved by Sanchez's protest that they used to be in the same unit. Having noticed that everyone on the DARPA team is wearing a silver disc, Schofield realises the disk generates a signal that keeps the gorillas from attacking their masters (which is the same one that allowed the gorillas to track them) and whispers for Mother to jam the signal.
With the discs rendered useless, the gorillas awaken from their control, and start attacking the DARPA scientists, killing Knox and Pennebaker. The Delta team is distracted, allowing Schofield's team to kill while leaving the Buck, who is in complete shock. Schofield opens the sea gate to flood the chambers, drowing the Buck and most of the gorillas; a few attempt to follow the Marines but luckily the final grate is closed in time.
With that, the Marines wait on the island's landing strip for a C-17 Globemaster transport that was intended to transport the gorillas off the island, and while the plane's crew is surprised that there is no special cargo for them, Schofield simply requests them to take him and his team home.
- 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
- Set on the 1st of August 2005, the novella takes place almost two years (21 months) after the events of Scarecrow.
- In the interview at the back of Scarecrow and the Army of Thieves, Matthew Reilly stated "Hell Island exists as a nice side adventure for Scarecrow and Mother, and a great short book for new readers who might wish to try my work."