The Xindi work merrily on their weapon - it'll be ready in a few weeks. Meanwhile, Enterprise is on its way.
Exposition in the command centre, then Archer, Reed and Hayes go down to the planet in a shuttle and wander around in the jungle til they find a Xindi base. They venture inside. Xindi security evidently sucks. They beam a canister to Enterprise for analysis. Archer wants to find out where they're shipping the kemocite because that's where the weapon is likely to be. They capture one of the Xindi (sloth variant) named Gralik and have a wee chat.
Gralik knows nothing about the weapon though, so Archer shouts at him some more. Meanwhile, Trip determines the kemocite is the same stuff used in the weapon which attacked Earth. Archer debates with Reed whether they should blow up the compound, and ultimately decides to. Jeeze, when the good guys are acting like bad guys, it's a wee bit worrying.
Archer shows Gralik the fragment of the original weapon and demands to know where the new weapon is being built. He still denies all knowledge. He says he sold the ore to Degra, a primate-Xindi, and then provides exposition on how the Xindi homeworld was destroyed. T'Pol reports a Reptilian Xindi vessel coming into range, and Archer and co spy on them.
Meanwhile, Phlox discovers that the organic component of Xindi hand weapons is vulnerable to delta radiation. Gee.
Gralik suggests to Archer that he meet with the reptilian-Xindi and see if he can get more information about the weapon they're building. The Reptilian-Xindi go looking for Gralik... ooh, look, probe droids. One of them spots Reed and gets away. Archer and co decide to go hide in some caves.
Trip attempts a test firing of the Xindi handweapon, but accidentally puts it on overload and has to beam it into space before it goes boom.
Archer has a Cunning Plan. He lets Gralik go, and gets Enterprise to beam down a canister with ore with an altered signature which they'll be able to track when put on the reptilian ship. Archer sneaks into the Xindi shuttle to make the switch (why didn't they just give it to Gralik?!) Gralik manages to keep the reptilians distracted while Archer escapes.
After the reptilians are gone, Archer thanks Gralik for his help, and Enterprise goes off in search of the reptilian ship. Teh end.