Homer and Marge, on the way back from a concert, pass through a seedy part of town. Homer cautions Marge, but gets enticed by Snake'sThree-card Monte game. Snake cheats Homer out of $20, which makes Marge mad. When she exposes the con, Snake takes off. Marge, not wanting to let a crook run and not getting any help, chases after him, Homer tries to stop her laboriously, but suddenly he feels the pain in him, causing to stop, lose breath and wheeze badly. Marge even runs faster than Snake. Snake, trapped in a dead end, tries to attack Marge, but a panicked Marge manages to knock him out. She begins to feel that the whole misadventure has given her a sense of exhilaration.
Soon, she begins to find that her everyday routine is dull and boring. In the grocery store, she starts rolling around on her shopping cart till it crashes, exciting her more. She begins to lose interest in her previous magazines ("Sponge and Vacuum"), and checks out the Death Sports section. She decides to spice up her life by joining the Springfield Police Force (much to the amusement of Chief Wiggum and the other cops, although he agrees after a while).
Homer, however, is less than enthused about his wife being a cop, but she assures him that he will remain "man of the house." Marge reports for police recruit training. She does well in the obstacle course, pretty well in the shooting range and nails the high-speed driving test—although Wiggum asks her to redo it, as he wasn't watching. Finally she goes home to her family, and announces herself to be part of the force.
The next day, after a breakfast of donuts and coffee (a cop's necessary sustenance), Marge reports to the station for work. Wiggum (after assigning some cops to stake out a donut place and some cops to sleep in), sends inexperienced and vulnerable Marge to Junkyville and Bumtown for her beat.
On her beat, after encountering Lionel Hutz rummaging in a dumpster, she goes to the Kwik-E-Mart, where Apu (who knows the drill) tries to bribe her. She then settles a domestic disturbance in the Skinner residence.
On her day off, she orders Bart to wear safety gear when skateboarding, which gets him beaten up by the bullies. She goes to the beauty salon, where the people there are a little skittish around her. Lisa tries to encourage her mom to "attack the roots of social problems" but fails when Marge doesn't understand what she means and changes the subject with a McGriff the Crime Dog hand puppet.
That night, Homer and his friends Lenny, Carl, Moe and Herman are playing cards. Herman excuses himself to get some fresh air. Homer fires up a Cuban cigar, thinking that he's immune from the law because his wife is a cop. Marge comes in and finds them gambling illegally. Homer's friends beat a hasty retreat while Homer himself is a little mad at her for not being home more often.
The next day, she seems rather unenthusiastic, as everyone seems to be breaking the law—especially Homer, who has parked illegally across three handicap spaces and is buying liquor for the underage bullies. She tells him to move his car, which he refuses to do still thinking that Marge won't arrest him, leading her to write him a ticket. He gets even more aggressive, which prompts her to arrest him. Later, he is released (after eating Hans Moleman's Last Meal) but he is pretty mad at Marge.
When he gets home, he finds a jean-smuggling operation going on in his own garage and his friend, Herman, is involved. As Herman and his cronies are about to tune him up, Marge busts in to save the day. As she is cuffing the rest of the crooks, Herman takes Homer as a hostage and runs to Bart's treehouse, with Marge in hot pursuit. She manages to evade getting shot, by coming in through the secret entrance. Herman tries to escape using a pair of knock-off jeans to slide down a rope. But the jeans are so lousy, they tear up and Herman falls to the ground.
Later, Wiggum informs Marge that they can't hold him for lack of evidence. Marge retorts saying that there is a garage full of counterfeit jeans, but Wiggum says that they have "mysteriously disappeared" -- true, considering all the cops are wearing them now. Marge gets mad and says that there is too much corruption on the force and she quits. After a hearty laugh, Wiggum accepts her resignation.