Ali and Frank are assigned to find out who murdered plastic surgeon Marvin Michaelsen after a drug dealer identifies him as the man who removed his fingerprints, but the tension between the two soon ends up taking a higher priority than the investigation. Nicco and Mickey work together on the case of Dermot Wells, a garbage collector that is believed to have murdered his former co-worker, and make a bet on how soon they'll get a confession.

A tax-evasion case leads to an investigation of a prostitution ring and murder.

Mickey and Ali investigate a twelve-year old murder that was believed solved thanks to a tip from a junkie named Simon. Coscarella investigates when two dogs trained by the same man attack people on command. Christine cannot resist the lure of her past, and steals cocaine from the lock-up.

Courts rule evidence in a murder case inadmissible prior to a retrial.

Police corruption may have played a role in drug-gang activities.

Frank and Nicco are stripped of their badges over the drug probe.

Cold Squad is convinced they have the necessary ammo to bring down killer Dean Bulmer, and Nicco goes so far as to promise the family of one of his unlucky victims that it's in the bag, but when a body found proves to belong to the man Bulmer is on trial for killing, the Squad realises that Bulmer has been fingered for the wrong murder, and it comes down to the moral question of whether to lie to keep a vicious killer in prison, or to tell the truth and have him set free.

When Ali's testimony results in the release of a killer (Dean Bulmer), Coscorella takes it too seriously and makes catching Bulmer his sole goal, much to the displeasure of homicide detective Len Harper. Nicco is furious with Ali and believes she should have lied to keep Bulmer in jail, and tries desperately to keep the father of one of the victims from taking justice into his own hands. Cold squad is in danger of being closed down, and the officers absorbed into the homicide division.