With help from Xindi allies, the Enterprise crew attempts to stop the arming of the Weapon aimed toward Earth. Meanwhile, the Xindi-Reptilians have kidnapped Hoshi Sato, hoping that she will be able to decipher the Aquatics' launch code. Seeing their plan coming apart, the shadowy Sphere Builders attempt to alter events.

Steven Culp (Major Hayes)
Scott MacDonald (Xindi-Reptilian Commander Dolim)
Rick Worthy (Xindi-Arboreal Janaar)
Tucker Smallwood (Xindi-Primate)
Josette DiCarlo (Sphere-Builder Woman)
Bruce Thomas (Xindi-Reptilian Soldier)
Andrew Borba (Xindi-Reptilian Lieutenant)
Mary Mara (Sphere-Builder Presage)
Ruth Williamson (Sphere-Builder Primary)

Paul Dean (Xindi-Reptilian Technician)
Porthos

• The Reptilians inject Hoshi with neural parasites to get her compliant, in order to decipher the launch code.
  
• The Sphere Builders increase the anomaly output of the spheres, allowing the Reptilians to escape the Xindi fleet. When the Insectoids question the Reptilians about the Guardians and the Spheres, Dolim destroys their ship.
  
• T'Pol determines that certain spheres are acting to link the entire sphere network. Damaging one of these could disrupt the entire network.
  
• T'Pol expresses an interest in joining Starfleet once this mission is over.
  
• Major Hayes is fatally wounded while rescuing Hoshi.
  
• The episode ends with Archer going after the weapon in Degra's ship, while Enterprise heads to Sphere 41.
  
• This episode won an Emmy Award for Outstanding Visual Effects.
  
• This is the last of four Enterprise episodes directed by Robert Duncan McNeill (Tom Paris).