Dexter Colt is a private detective hired by Homer to spy on Lisa and report his discoveries so Homer could appear to know facts about her life.
However, Colt charges Homer $1000 for expenses, including a $40 steak, which would've been free had Colt eaten all of it, as well as silver bullets, because Colt initially suspected Lisa of being a werewolf. When Homer refused to pay, Colt framed Lisa for stealing all the animals of the Screaming Monkey Medical Research Center.
Colt later confronts Homer and Lisa at a circus. After Colt shoots a human cannonball at him, Homer hides in a hall of mirrors. Colt pursues Homer and attempts to shoot him, but he is foiled by Lisa, who blinds him with a laser pointer. The copos then show up and take Colt away to prison.