The Starship Enterprise is carrying a group of ambassadors of the United Federation of Planets to the Babel Conference. An unknown vessel is trailing them.
The ambassadors are arguing fiercely, and Sarek, the ambassador for Vulcan, accuses the Tellarites of wishing to exclude Coridan from the Federation in order that they can plunder its dilithium. Soon afterwards, the Tellarite ambassador is found murdered, with evidence pointing to Sarek.
Thelev, an aide to the Andorian ambassador attacks James T. Kirk, and is placed in custody. The Enterprise tries now to track the ship following them, and discovers it is in contact with someone on the ship. It is discovered that Thelev is really and Orion spy, associated with the ship, and infiltrated aboard to disrupt the conference. The ship destroys itself and Thelev commits suicide.