Odo is rushed to the Infirmary when he suddenly collapses. After a thorough examination, Dr. Bashir determines that Odo is losing the ability to maintain his solid form, but is unclear as to why. His condition worsening, Odo realizes that the only place he can find help is with his people — the Founders, rulers of the Dominion. Odo, forced to return to the homeworld of his people must face judgment for killing one of his own. Odo joins the Great Link and is found guilty and they punish him by turning him into a "solid." Odo realizes that Gowron, Chancellor of the Klingon Empire, is a Changeling.

Salome Jens (Female Shapeshifter)
Andrew Robinson (Elim Garak)
Robert O'Reilly (Chancellor Gowron)
Jill Jacobson (Chalon Aroya)
Leslie Bevis (Boslic Freighter Captain)

• Season 4 finale.
  
• Salome Jens was the humanoid in the DNA message in the TNG 6th season episode "The Chase".
  
• Odo killed a changeling in the 3rd season finale "The Adversary". He was the first changeling to ever harm another.
  
• Odo becomes a changeling again in the 5th season episode "The Begotten".