In season 4, we see Monk getting closer to his new assistant Natalie (Traylor Howard), a single mother who aids Monk not only with his crippling phobias, but also with his crime-solving exploits. A showdown with rival private detective Marty Eels (Jason Alexander) sets in motion a new season in which we discover crucial details of Monk's past.
When fellow detective Marty Eels (Guest star Jason Alexander) shows up at a crime scene knowing all the answers, has Monk finally met his match, or is Eels cheating?
Monk solves a Halloween murder mystery while he and his brother Ambrose (Guest star John Turturro) wait for their long-lost father to return home.
Natalie puts herself in jeopardy to pursue a case when Monk is sick in bed with the flu.
When a parking garage attendant is killed and a financial analyst's hand is broken in a mysterious attack, Monk goes undercover in an office to solve the case.
A relaxing getaway in wine country turns into a crime-filled weekend as Monk and Natalie try to uncover a murder involving a man that doesn't exist.
Monk must get to the truth when it appears that his late wife Trudy is still alive.
Monk must prevent a killer from spoiling the party at Natalie's brother's wedding. Holland Taylor guest stars.
When a childhood crush comes to Monk with a mysterious murder, Monk tries to win her heart by solving the case.
When a detective dies at the police department Christmas party after drinking from a poisoned bottle of port intended for Captain Stottlemeyer, can Monk find the killer?
Monk enters the world of high fashion when he believes a young man accused of a model's murder is innocent.
When Monk wakes up in an unfamiliar town with amnesia, can he solve a local murder mystery and find his way home?
Captain Stottlemeyer has to go to anger management class when he slugs a cop who claims he's having an affair with the Captain's wife.
Monk and Natalie try to solve a diamond heist that promises a big reward. But in their race for the money, they face three unscrupulous competitors.
Monk tries to prove that an astronaut committed murder despite the suspect's seemingly airtight alibi: he was in space. Jeffrey Donovan guest stars.
Lieutenant Disher quits the force when no one believes that he witnessed a murder while under anesthesia at the dentist. Jon Favreau and Brooke Langton guest star.
While sequestered on jury duty, Monk juggles two cases: proving that the accused is not guilty and figuring out who was killed outside the courthouse.