Stargate Atlantis

When a routine, off-world science mission comes across a mutilated Wraith carcass, the team suspects Ford may be involved. Intrigued, they split into teams to investigate. Teyla and Sheppard encounter Ronon Dex, a fierce warrior who survived a battle with a Wraith seven years earlier and has been on the run ever since. When Dex reveals to Teyla and Sheppard that Ford has taken up residence on the planet, they enlist his help to locate their friend. The duo hope to rehabilitate Ford to his former state. McKay eventually stumbles upon the increasingly incoherent and maniacal Ford, and tries to reason with his former colleague and friend. However, McKay begins to see how far gone Ford has become -- addicted to the enzyme injected in him by the Wraith who attacked him, Ford has been brutally killing Wraith to get a fix of the solvent. Reluctantly, McKay and the rest of the crew must face the realization that they may never be able to save Ford from what he has become.