- Jeremy, James, and Richard are in central Africa to find the source of the Nile River.
- Part 2 of 2.
After spending the night in beautiful countryside, James wakes up to find out that Jeremy has taken a piece of metal from the bonnet of the Volvo to fix what James had done to his BMW, which leaves him in a bad mood; not because he took it but because he did a shoddy job of it. As well as “fixing” his car, Jeremy attaches a log to the back of his BMW to make braking and hill starts better. However, although it works, this backfires when the log, which is left loose, bounces up and shatters his rear window.
After driving across Rwanda, and crossing into Tanzania, both James and Jeremy find replacements for what they lost from their cars off of their other colleague’s, Richard’s bonnet and rear window, and Jeremy decides to help Richard replace those missing bits, by putting his toilet on the bonnet and a piece of cardboard for the rear window.
As they travel eastwards, the trio are stopped by a river and realise it is too deep to wade through with their cars, especially since there are crocodiles lurking within it. Using a flying machine with a camera Jeremy invented for the trip, they learn there is no bridge or crossing point both up-river and down-river; Jeremy therefore comes up with the idea of making their own car-ferry, designed specifically to take their cars across the river, using wood and rope to fashion it. Even though both Jeremy and Richard manage to get across with it but nearly get stuck at the other end, and James almost sinks the ferry with his car since the weight of it isn’t evenly distributed (which the danger was further heightened when Jeremy decided to pull the ferry using his car), the trio manage to get across safely. However, when the producers tried to get the Ford Scorpio back-up car onto the ferry, the ferry wasn’t secured, so the car missed it and went straight into the river, much to the three’s amusement, so the trio left the producers to clean up their mess.
Upon reaching Lake Victoria, the three decide to use a proper ferry to get across it to Tanzania. When they reach the other side the next day, Richard decides to disembark at a beach and show off his 4X4 Subaru, but gets it stuck in the sand, and when trying to repay the 40 locals that helped him to get it out, he ended up losing his lunch to them. The others disembark at a proper jetty and later reunite to find the river they believe leads to the source.
While stopping for a moment, all three decide that the cars are all great, but when separate from the others, they each claim that their car is the best. Eventually, they finally find the river they were looking for and begin to follow it to the predicted source of the Nile. However, they come across a really rough road they have to travel on, which Jeremy describes as a true “Car-Killer”, and soon it starts to take its toll on the cars as they try to make their next camp. Jeremy’s airbags has been deployed, James had several punctures and one of alloys was damaged and replaced, but Richard’s car suffers the worst damage when the left wheel’s rod steering, which was rusted to begin with, finally snaps apart, leaving him to try to fix it, with the back-up car no longer available. Despite usual Top Gear behaviour in such a situation, the other two, who made camp, decide to wait for Richard for a while longer the next morning before setting off. Just as that deadline is nearly reached, James and Jeremy spot their third arriving, Richard having fixed his car enough to survive the last leg.
Challenge, Part 2: James and Jeremy decide once Richard is back, that since only one person can be remembered for finding the source, and the other two will be forgotten, that they should have a race to find the source. At first, Jeremy decides to go slow to avoid more incidents, but soon speeds up when he realised he was getting nowhere. After many blind decisions had been made, and many wrong turns, they soon find they have to leave their cars and find the source on foot, James having to since his rear suspension had just collapsed.
Soon, in the end, James finds it first, which turns out to be merely a very small pond being fed from somewhere beneath large rocks, just seconds before Jeremy does, with Richard arriving a little later. The pair congratulate James, and two flags, the Top Gear one and the British Flag, are planted at the spot, with the three posing for a photo like the Victorian explorers. A caption over the photo, says “James May, Discoverer of the True Source of the Nile, and Two Other Blokes.”
As the credits roll, each member of the crew, like in previous specials and such, has their name altered with each displaying their surname with “Dr.” before and “I Presume?” afterwards (such as “Dr. Clarkson I Presume?” and so forth).