Enterprise mediates a peace treaty between the Tellarites and the Andorians. Captain Archer and Communications/Linguistics Officer Sato spend some time preparing for a visit by the Tellarite ambassador. The argumentive nature of the Tellarites is discussed. Sato tells Archer to keep Porthos out of the way as Tellarites think canines are a delicacy. After receiving a transmission from an unknown Andorian ship under attack, the Enterprise alters its course to assist. Upon arriving they find that the ship's Captain is Shran and that his ship has been destroyed by what he claims to be a Tellarite vessel.
After Shran and the other Andorians (along with the Tellarites) are on board the Enterprise, the ship is attacked by an Andorian ship. When communicating with the ship fails, the Enterprise returns fire. Shran tells Archer where to fire on the Andorian ship in order to knock out its shields, but the attack is ineffective - the ship's shields are still at full strength. The Enterprise is only saved when the Andorian ship has to retreat because of internal damage. After some tension between the Tellarites and Andorians on board the Enterprise, the crew manages to track down the "Andorian" ship which is revealed to look completely different from their previous encounter. Security Chief Lt. Reed and Chief Engineer Commander Tucker beam aboard the ship to get readings on it.
It is revealed that the ship is not being piloted by either Tellarites or Andorians, but instead it is a group of Romulans using a telepathically controlled ship capable of disguising itself (via holograms) to attack assets of different worlds in an attempt to destabilize the sector. This episode ends with a 'To be continued...' And the story picks up in the next episode, "United."