Scientists arrive to their lab only to find that someone has released the monkeys used in research from their cages; and the body of their colleague, biochemist Ronald Lee.

Lee's autopsy shows that he died due to an anaphylactic reaction to a monkey bite. All but one of the monkeys are missing and are carrying the AIDS virus. The detectives only have 72 hours to locate the monkeys before they are required to go public with the news.

The detectives' investigation leads them to two protestors who had participated in an earlier demonstration against the use of animals in the lab. One has an alibi; the other one, Maxine Walden, was released by one of the guards on duty, George Peavey, who ended up taking an interest in animal rights.
!!Tropes present in this episode
* AnimalTesting: The episode takes a BothSidesHaveAPoint approach: the researchers at the lab infect the monkeys with AIDS, but they try to minimize their suffering as much as possible and believe what they do is for the greater good. On the other hand, Peavey does not release them into the wild. Instead, he gives them to a shelter which knows how to care for them and which is informed of their condition. He does not take any joy in Lee's death.
* AnimalWrongsGroup: Subverted with All Living Creatures United. They were not involved in releasing the infected monkeys.
* DidntThinkThisThrough: George Peavey decided to steal disease-carrying monkeys for the sake of saving their lives and even took them to a shelter so they would be cared for, but did not think about the risk of any of the monkeys escaping.
* HonorBeforeReason: [=McCoy=] gives George the option to plea bargain down to a year in prison (if he behaves himself), which his lawyer says is fair, and Maxine urges him to take. As a true believer to the animal rights cause he puts his faith in the wisdom of the jury, which goes badly for him. [[InspirationalMartyr Not that he minds of course...]]
* LoveMakesYouEvil: George fell hard for Maxine, and did everything he did to impress her. Subverted, in that he and his beloved both believed in the cause but played staright in that somebody died as a direct result of his actions. Bonus points for Maxine shouting "I'm sorry!" to both George and his mother as the verdict is read out.
* MeaningfulName: Maxine Walden shares a name with one of Creator/HenryDavidThoreau's more famous works, ''Walden''. Another famous work by Thoreau? ''Civil Disobedience''.
* ScrewTheRulesImDoingWhatsRight: George certainly believes this, and it's the motive for "rescuing" the monkeys.