Kate and Nick are forced to release the original Chameleon that was imprisoned by the SU2 team so he will help them catch a new Chameleon who is now terrorizing Chicago. Nick is in a bad mood because the original Chameleon that has to help them killed his former lover.

A fabulously wealthy - and beautiful - cosmetics executive is Nick and Kate's key suspect after a 19-year-old male model is found mysteriously dead of old age. Using Nick as bait, the SU2 detectives must prove the glamorous tycoon is a witch who has lived for centuries by literally sucking the youth out of her victims to keep herself young.

Nick and Kate must stop the execution of a boy's father who has been wrongfully convicted of a murder committed by an invisible Boogeyman Link.

A Link so monumentally evil that his name has been lost to history reappears on Halloween, the one night of the year when Links can roam with impunity. The confrontation between the Link and Nick is made all the more personal - and lethal - as it is the villain responsible for the death of Nick's former partner. The mysterious Link is bringing the corpses of serial killers back to life so they can carry out his plan to assume leadership of all Links.

When Kate kills Medusa's sister, Medusa exacts vengeance by striking out at Kate's boyfriend; Nick skirmishes with the Gorgon, and Kate must race to find an antidote before her partner turns to stone.

Graverobbers take a necklace from an Indian burial ground, unleashing a fire-breathing dragon that goes on a rampage through Chicago. Unfortunately, the only one at SU2 who has ever successfully fought and killed a dragon is... Carl.

A series of gruesome murders leads Nick and Kate to suspect that Jack the Ripper has returned from the grave... and is stalking victims in Chicago.

Cajoled by Nick into attending her high school reunion, Kate is forced to relive the humiliation of how she ruined her graduation 10 years earlier by taking over the ceremony and hysterically insisting that Links lived in the walls of the school. Acting as her escort to the reunion, Nick helps Kate redeem her reputation when the Links return and attempt to massacre her classmates.

The Scarecrow, a particularly noxious Link, is inadvertently unearthed and loves nothing more than the fear and mayhem he creates by reading - and exploiting - the "fear center" in every Chicagoan's subconscious. As the city degenerates into mass hysteria, Nick and Kate learn that to defeat the Scarecrow, they must first deal with all their own fears and phobias

When Cupid's 'love potion' causes a hangin' judge to start setting high-end criminals free, it's up to Kate and Carl to get an on-the-lam Cupid back to Chicago to reverse his potion's' effect on both the judge and a transformed Nick, whose newfound propensity for seeing the good in everyone begins to wear thin on his colleagues.

A Link with mind control powers sets off a crime spree using children as the perps. When Nick and Kate's investigation leads them to a really annoying kids show host, they send a bitterly reluctant Carl undercover as the host's sidekick to discover - and destroy - the Link's power.

The Djinn, a Link who makes dreams come true, but at a price, is on the loose in Chicago. If she can grant four wishes to four different masters, she will gain power to enslave the city. Now it's up to Nick, Kate and rest of Special Unit 2 to prevent her from granting her last wish.