When Enterprise responds to a distress call from the Vulcan cruiser Seleya, stranded in the Delphic Expanse, Archer and his boarding team (T'Pol, Reed, and Hawkins) arrive on board to find its crew in a deranged, raging, zombie-like state that quickly manifests in T'Pol as well. 

Archer, Reed, and MACO Major Hayes infiltrate a Xindi-Sloth industrial colony that synthesizes the vital explosive material for the Xindi super-weapon that will attack Earth. The trio kidnaps the plant foreman, who allies with them once he learns of the Xindi council's attack on Earth. Elsewhere, Trip, T'Pol, and Dr. Phlox test captured Xindi firearms to create better defenses against them.