Marvin works to track down a missing teenage girl after her romantic interest is discovered decapitated along the side of the road.
Marvin's investigation into an unknown serial killer, coined "the Boner" by local media for mutilating their victims with animal bones, is interrupted by a production crew who's in town to turn the case into a true crime limited series. Meanwhile, Stan grows close with the actor playing Marvin.
After being forced to take a desk role in the office, Flute decides to lead a double-life and become a dog-themed superhero named McSnuff.
Flute enters the Grimsburg Miniature Competition and is accused of murdering the judge, Jebediah Cupps, after he disqualifies him. Flute tries to clear his name at the local middle school by recreating a miniature model of the crime scene. Then Stan joins his school's Trauma Club.
The Grimsburg police department goes undercover at a wedding to catch the notorious bouquet-catcher killer. Kang, Summers, and Wynona try to perform convincingly as the wedding band but Flute is distracted when Harmony catches the bride's bouquet, putting her in the killer’s crosshairs.
A murder mystery party becomes all too real for the Grimsburg PD when the wealthy, eccentric host is killed. During the investigation, Flute finds himself threatened by Stan’s detective skills, Summers tries flirting with Wynona and Kang and Pentos form an unexpected bond.
Flute and the team get the campy horror movie experience when, after a series of counselors are found murdered, they attempt to make the town’s summer camp slasher-proof. Meanwhile, Harmony tries to get Stan outdoors and away from screens.
In a failed attempt to catch “The Cartwheel Killer,” Marvin is eager for a new partner who won’t slow him down. Someone sleek and tough, with the mustache befitting its own 80s TV show, Marvin looks for a partner just like him, if not better.
Stan creates a diabolical plan to stop Marvin from forgetting about him.
Marvin and the team investigate the death of a morning TV host, in which former child star Lil’ Betsy is the main suspect. In the process of the investigation, Marvin becomes consumed with his newfound celebrity status. With everyone rallying around Lil’ Betsy, Marvin is determined to find her guilty.
During the town’s talent show, a serial killer targets the winner as Marvin finds himself at the judging table to capture them in the act.
In an attempt to become immortal, Marvin drinks a special potion that causes rapid de-aging. Meanwhile, the department hires a new lieutenant.
On a day where murder seems to be on the low, the biggest of Marvin’s problems is his missing danish. The quest for the sweet boysenberry danish leads to an explosive case no one saw coming.
Harmony pushes Flute to move out, resulting in him moving into a house haunted by a doting housewife. Things soon go awry when Flute invites everyone for an adult party at his house, and Flute’s disregard of the ghost prompts her to threaten their lives. Also, Flute clashes with new child detective Otis Volcanowitz.
When Flute forgets to buy Stan a gift for his birthday, he steals an A.I. Doll from the evidence locker named MO11Y, unaware that the doll is actually a murderer. Meanwhile, when an investigation leads the precinct to Grimsburg's "Dolltown," Wynona is forced to confront her ex-boyfriend, Buddy, while Summers struggles to find the right moment to finally ask her out.
After nepo baby Otis the Kid Detective is put on the force per pressure from the Mayor, Flute makes it his mission to get the kid to quit the force. But his plans to scare Otis away go too far, just as Flute grows a soft spot for him.
Flute and Kang butt heads over Flute's relationship with Kang's Great Great... Great Granddaughter. Flute does not want to stop seeing her, but Kang forbids it, even though he has yet to tell his relative that he is her distant ancestor. After a bomb threat is called on Grimsburg's annual Virgin Pageant, the Grimsburg PD need to have a man on the inside and have Summers pose as a contestant. Wynona, a former winner, coaches him a la Miss Congeniality.
When his dad returns to town, Flute will do anything he can to keep his idol around, even if that means getting rid of his sibling rivalry - his dad's talking car. That's right. Flute's Dad is basically Michael Knight and his "step-brother" is KITT. With Flute spending time with his father, it's up to the detectives to teach Stan about the birds and the bees.
It's time for CrimeCon-Grimsburg's famed crime-themed convention. When Flute learns that the criminals at CrimeCon are celebrated, not the detectives, he makes it his mission to prove that celebrity criminal, Damien Flesher, is not the reformed cannibal he claims to be. While chaperoning his students at ConCon and questioning where he is in his life, Pentos meets the Pentos-tonix, a Pentos-themed acapella group. Pentos then has to prove to them that he has still "got it" and is the criminal mastermind they grew up idolizing.
