Three aliens in suits which make them look like the aliens from U.F.O. hunt down an unarmed alien with flamethrowers.
Trip takes T'Pol some peaches and they have hot spine poking. Then ARcher calls her to the ops room and they look at the Xindi database, heading for the last planet the Xindi ship the DB was from which leads them to wader around the same planet from the teaser, where they find an abandoned Xindi ship and the crispy alien.
Then the landing party starts mutating into freaky aliens. T'Pol rings the ship but the other away-team members start chasing her. Eventually they catch her and start making funny noises at her. Eventually she persuades Archer to untie her and gets Hoshi's universal translator.
Trip and go are confused about the bio signs they're getting from the planet, so Trip decides to take another team down in bio suits.
T'Pol communicates with her altered crewmates some more. Archer and Reed fight a bit. Alden wonders if this is what's passing for scripts these days. Then they eat melons.
There's an altercation with Trip's landing team, who stun Reed and take him back to the ship. T'Pol opts to stay on the planet with Archer and Hoshi.
Phlox says Reed's been infected with the mutagenic virus, and he needs T'Pol's DNA to formualte an antidote. Then more alien ships turn up and tell them that Enterprise has been quarrentined. They also want to "neutralise" Reed, but Trip tells them to feck off.
Archer dreams about a vast underground city, which would make a good Unreal Tournament level. He wakes up and tells Hoshi and T'Pol about it.
Tripa nd Phlox get an info download from the new aliens, who are going down to the planet to search for Archer and co. Oh, Trip has that "I have a plan" look. He goes and grabs one of the peaches from T'Pol's quarters.
Archer's party reaches the city from his dream to find it long destroyed. Bummer. Then the other aliens turn up, and they have to flee. There's a tussle, and Archer and co win. They;re ambushed by more aliens on the surface, but Trip and co transport down to the rescue. They return to Enterprise in the shuttlepod.
Once they're back, Enterprise goes to warp, pursued by the alien ships. Then Archer and Hoshi appear on the bridge, having started on the antivirus.
Holy crap, he synthesized an anti-toxin that fast?
They give the antivirus to the other aliens, and Archer says that they should put a sample of the virus on ice otherwise they'd be wiping out a whole race. Er, what about the one you callous sods left to die in season 1?!