The Amazon rainforest, 1827. The Doctor, Amy and Rory arrive in the jungle near a hurriedly abandoned campsite, where they are surrounded by hungry black caiman - huge lizards. Only the arrival of a man with a rifle sees off the giant beasts. Oliver Blazington has come to the forest to bag big game, and his companion Garrett is a naturalist, collecting exotic creatures for London Zoo. But the Doctor soon discovers that another very different hunter is stalking the Amazon. Animals and people have been disappearing without trace, and local villagers speak darkly of 'The Eye of the Jungle'. Amy senses that the all-seeing Eye is watching them - but she and Rory are powerless to intervene when it sets its sights on the Doctor...
The Doctor, Amy and Rory arrive in the Amazonian forest in 1827. They are quickly attacked by a group of caimans. They are saved by hunters led by Oliver Blazington, who take them to his camp. They meet the leader of the expedition, Edwin Garrot, a naturalist whose goal is to bring back animals for the opening of the London Zoo in 1828. The TARDIS crew rapidly learn about disappearances in the village, for which they blame a spirit called the eye of the jungle. The Doctor, Amy and Rory decide to stay for the night. Scanning the area with the sonic, the Doctor looks at the sky and sees a strange light then hears a scream. The hunter has been taken by a jaguar and the priest of the village. Deciding the place is not safe the Doctor takes Amy and Rory back to the TARDIS, a trip that takes them the rest of the night. They find that the TARDIS is gone and they are attacked by a huge jaguar. The Doctor distracts it to let Amy and Rory escape,, but a red beam strikes it and it disappears. An oval, corroded robot probe arrives. As the Doctor tries to scan it he is struck by the same beam. The Williams' go back to the landing area, only to find the sonic screwdriver lying on the floor.
The Doctor has been teleported into a dark place. He is in a space station over South America. Three rodent-like creatures appears.. They explain to the Doctor that they have a war to win.
Rory finds the probe and understands it is the eye of the jungle. Amy andhe are attacked by a snake. The probe shoots its beam at the snake, then at Rory. Amy realises the beam may not be lethal, Sshe grabs the sonic screwdriver and present it to the probe.
On the space station, the Doctor learns the the creatures, who are called Nadurni, want to use the animals they take as biological weapons manipulating their genes to win a war. The Doctor understands they have already done it to themselves too much, deforming themselves.
Amy arrives on the station near the TARDIS, Rory and several other things and animals.They find deformed creatures in cells which turns out to be Nadurni experiments. In one, they see Blazington mixed with a jaguar. He asks them to help him get out. Amy does, but also frees all the other creatures. Blazington helps them to get to the Doctor.
The Doctor is held captive by the aliens who want to mix him with a caiman and a tarantula to create the perfect soldier. However, Amy, Rory and Blazington arrive. Blazington saves the Doctor from the gene manipulator but get stuck in it. The result is a big creature, part human, jaguar, caiman and tarantula. He starts to chase the three Nadurni, smashing everything in his way and advising the Doctor and his friends to flee before he starts to hunt them. The Doctor grabs Amy and Rory, and they use one of the probes to get back to the TARDIS avoiding the chaos induced by all the creatures. After a fight with the monsters, the Doctor connects cables and restores the creatures before teleporting them back home.
The TARDIS crew return to the village in the ship before the station explodes, leavingBlazington and the three aliens dead. In the village, every missing person is back and Garrot is ready to return to England with the animals in their cages. Hhe says the animals are not all for the zoo, but also for private collections. The Doctor uses his screwdriver to open all the cage to let them escape, leaving Garrot ruined.
Back in the TARDIS, the Doctor states that "I was at the opening of the London Zoo next year. As far as I remember there were no jaguars on display."
- Blazington fought alongside the Duke of Wellington at the Battle of Waterloo.
- The Doctor says "Geronimo!" again when escaping aboard the spacecraft.
to be added
- On several occasions, Amy is referred to as Amy Williams, which contradicts the TV series which has established that she kept her maiden name after marrying Rory.
to be added