Special Unit 2 (SU2) is a secret division of the Chicago Police Department. They are such a mystery that no one outside of their unit is aware of what they really do, they just know to stay out of their way. The SU2 headquarters is an abandoned subway station that you can only enter through the hidden door at the back of the Golden Eagle dry cleaners. The mission of SU2 is to track down and rid the city of what they call "Links". A Link is a creature that evolved from the missing link between man and beast.