Crusoe and Friday find a pirate's skeleton impaled with a spear. The spear's design links it to the cannibals who brought Friday to the island, meaning they've been here before. Crusoe wonders why they didn't eat him. Friday says their victims must be ritually killed to be eaten. This man escaped and they hunted him down, meaning a sacrifice site is nearby. Friday says the cannibals roam the islands, terrorize other tribes and fear no one. They find the site where Crusoe discovers evidence of a recent ritual. Friday wants to stay away from this side of the island, but Crusoe won't be scared off by them.
Clearly frightened, Friday explains that the cannibals have no race, tribe or family. He says the long pig has gotten them, meaning humans. "Live off humans long enough and you go crazy." Crusoe compares them to a gang rather than a tribe. Friday doesn't think Crusoe understands, but he does. Crusoe remembers being beaten by a gang in a London alley who tried to force him to say, "God save the King." They rig traps to alert them if anyone crosses paths to the treehouse. Good thing, because the cannibals have just landed on the island and carry two hooded prisoners with them.
Friday explains the type of cannibalism his tribe practices. They don't eat the meat of men, just the bones of their family members. After they die, they grind up the bones and add them to their food to gain the strength of their ancestors. In the jungle, the cannibals trip one of the traps and free the parrot. While fishing, Crusoe sees it fly overhead. At the treehouse, they see the parrot and know the cannibals have landed. Crusoe wants to steal their boat, and convinces Friday to help him by telling him to imagine the look on the Cannibal King's face when he sees his boat is gone.
Friday, Crusoe and Dundee go to the beach and see the cannibals' boat, unguarded. As they approach, two cannibals spring up from under dead palm tree fronds and attack them. They fight, Crusoe shooting one and the other falling and impaling himself on the boat. Crusoe buries them back under the fronds as Friday finds the yoke the cannibals used on him, and realizes that they've brought captives. He tells Crusoe, who has found one of the captives' cross necklace, meaning they aren't native. Though disappointed they can't leave the island just yet, they know they must rescue the captives.
They find the cannibals in the jungle preparing the feast and see the two hooded captives. Friday says they use a powder to preserve the meat they don't eat. Crusoe realizes he's talking about saltpeter, which is also explosive. When the cannibals pass through the hog traps, they drop the net on them. In the struggle, Friday comes face to face with the leader, who recognizes him. Crusoe grabs one captive but Friday is unable to rescue the other. They get to safety, unmask the captive and are angered when they see it's none other than Santana, who left them on the island to rot.
At the treehouse, with Santana bound to a chair, Friday wants to kill him. Santana begs them to save the other captive, who is an islander like Friday. Both aren't moved, they know he only cares for himself. Santana swears he's a changed man. He says they stopped for water at an island where the cannibals captured him. He witnessed horrible things, and the man he was bound with gave him hope and brought him back to his God. As Crusoe and Friday ponder if he's being truthful, Santana prays. He shifts, the chair creaks. Realizing he can escape, Santana smiles.
Crusoe and Friday prepare their weapons to fight the cannibals. Crusoe's considering letting Santana help them, but Friday thinks he trusts too easily. This reminds Crusoe when his merchant ship was seized. His partner and brother-in-law Samuel Tuffley informed him that the seized ship was his, so instead of them all sharing the loss, it's his alone. Crusoe learned that Tuffley's lawyer only had his interests in mind and didn't explain the contract to Crusoe. Susanna wanted to go to the law, but with the political climate against merchants, Crusoe knew the law was on Tuffley's side.
Santana, having freed himself, surprises them at gunpoint. He says he wasn't lying, and that he's doing this to rescue a true friend. He makes them turn around and says his ship is two days from here by canoe. If he succeeds in rescuing his friend, Friday and Crusoe will be on it. He asks how that makes them feel. Crusoe, not believing him, tries to lure him with telling him the location of the gold cannon. But, when they turn, Santana is gone. Thinking he's gone to steal the cannibal's boat, they rush to the beach. But the boat is still there, without Santana.
They rush back to the jungle where Santana is stalking the cannibals. As he's about to attack, Crusoe tackles him. They go back to the treehouse and plan an attack. Crusoe gives Santana his word to fight alongside him. They shake, and Santana says, "And that of your man?" Crusoe says Friday isn't his man and his word is his own to give. Santana apologizes, saying Baillom is as much his brother as Friday is Crusoe's. At the mention of the name, Friday becomes furious and accuses Santana of trying to trick him. He runs off, leaving the two confused.
Friday sneaks to the cannibals' camp and sees Baillom, the captive. He whispers to him that he will rescue him. The captive asks who he is, and Friday says, "Father, it is your son." His father, who knows he was taken, can't believe he's still alive. Friday tells him that he was saved, and that he will return for him.
Santana and Crusoe are still confused why Friday ran. Santana says, "You know your man." Crusoe corrects him again, that Friday is his friend, one of the best he's ever had and he's been fortunate in friends. Crusoe remembers asking Blackthorn for a pass to leave the city to go to the West Country. Blackthorn asked why he wanted to go there, as that's where the Duke of Monmouth was raising his army. Crusoe assured him he just needed to get to his weavers and bring in new stock to save himself from further ruin. Blackthorn, satisfied that Crusoe wasn't plotting against the king, arranged it for him.
Friday returns and tells Crusoe and Santana that he went to the camp to see if Santana was lying about Baillom, whom he reveals is his father. In the jungle, as a terrified Baillom watches, the cannibals start their ceremony. Armed and ready, the three depart the treehouse to attack the cannibals. Crusoe returns the cross to Santana, who gives Crusoe his word he'll do everything to get him back to England if they survive this. When they get to the camp, the cannibals are gone. Crusoe picks up a sack of saltpeter just as the drums from the ceremony of sacrifice beat from far away.
Tied to a stake, Baillom is being prepared for sacrifice. Crusoe, Friday and Santana sneak up to the area. Seeing his father like that, Friday wants to act. But, Crusoe has another plan. Just as a cannibal is about to plunge a knife into Baillom, Crusoe interrupts and glibly asks if they remember him. "I shot a couple of your mates," he tells the Cannibal King, then tosses the saltpeter into the fire. The explosion temporarily blinds the cannibals, allowing Friday and Santana to free Baillom. A couple cannibals recover and fight back but Crusoe kills them. However, Santana is badly wounded.
Safe in the jungle for a few minutes, Baillom assures Crusoe that he can navigate to Santana's ship. Crusoe tells Friday to go with them, but out of friendship he stays with Crusoe. The surviving cannibals arm themselves and chase them. Santana tells Crusoe he'll return for him or die in the attempt. Crusoe has no doubt that he will. He's also won over Friday, who trusts him to make sure his father is safe. Baillom tries to convince Friday to come with them, but he won't. Proud of his son, he tells him he was always in his heart, and never lost to him.
Crusoe and Friday divert the cannibals away from Santana and Baillom so they can get to the boat. When they get there, the extent of Santana's injuries becomes very apparent when he collapses. Baillom pushes them off shore and paddles them to safety. Crusoe's man trap takes out three cannibals, leaving only the leader. Friday wants him for himself, and chases him to shore. They fight, and Friday takes a few slugs and head butts before he gets the better of the big man. Finally, he suffocates him by pushing his face into the sand.
Crusoe thinks this may be really it now, that this time they will be rescued. Friday is just happy that his father lives and knows he's alive. At sea, Baillom paddles the boat, which is alone in a very large ocean. At dinner, Crusoe says he has to build up so he won't look scrawny to Susannah. He asks Friday if he accounted and disposed of all the cannibals. Friday says almost, coyly looking at his plate, "As soon as we've finished this." Crusoe gags, and then realizes his friend is teasing him. They both laugh.