Newly retired detective Harry Trumble returns to the force when it appears 'The Clown Killer', a murderer Trumble chased for more than a decade, has emerged from obscurity to kill again. Mark is reluctant to help Harry investigate the Clown, in part due to a rift between the two, but also because Mark suspects Harry has something to do with the Clown's reappearance.

A young woman is assassinated while Dr. Mark Sloan is examining her, setting off an investigation that plunges Mark into dark memories of his own childhood.

Steve heads up the investigation when a serial cop killer is on the prowl, while inadvertantly dating the killer.

Mark aids an old friend, Joe Mannix, in solving a 25-year-old, unsolved murder.

Dr. Sloan and Amanda investigate when the co-pilot of the airplance carrying them to a medical conference is murdered and the remainder of the flight crew are incapacitated with a mysterious illness.

Steve goes undercover as a doctor in a private community after several mysterious deaths occur within its confines. Steve is 'aided' by a tabloid reporter posing as his wife.

Hospital horticulturist Claude is revealed to be an escaped convict living under an assumed name for the past 10 years. Mark fights to shelter Claude from extradition while striving to prove his innocence.

Steve nearly dies in a car accident and think a murder happens. No one believes him.

An abusive man who, along with four other people, was a contestant on a reality show is murdered while living in a house that is monitored 24 hours a day. After the killing, Mark enters the house as the man's replacement to see if he can uncover what happened.

Mark must find out why his dad left him as a child.

Dr. Sloan tries to save Jesse and Amanda from a murderer who is out to kill them in order to obtain a multi-million dollar inheritance.

Dr. Sloan investigates a free health clinic after several homeless people turn up dead... with missing organs.

A burglar inadvertently becomes infected with a deadly virus. Dr. Sloan and Jesse are subsequently exposed to the virus after Jesse stumbles upon the thief's dead body. Both Mark and Jesse are confined to Mark's home while Steve and Amanda investigate the drug company that manufactured the virus, in the hopes of discovering an antidote before Jesse runs out of time.

Mark investigates a 30-year old murder when the body of his old mentor is discovered entombed in a wall in the hospital.

Dr. Sloan investigates when an unpopular colleague drops dead while performing an operation. Mark investigates his fellow doctors when tests reveal the deceased was poisoned.

Dr. Sloan is stalked by a mad bomber whom he helped incarcerate. Norman and Mark are the main dissenters in negotiations to sell the hospital to a corporate raider.

Community General is already under increased security, with a high-profile criminal hospitalized, when an important businesswoman is brought in. Mark suspects her security guard has deadly intentions.

A spat between a girl and her boyfriend leads to an apparent murder, leaving the girl and her mother with a dead body, just as dinner guests Mark and Amanda arrive. Panic sets in, when the body disappears, the power goes out, the roads are impassable, and the attacks begin.

The body of a dead real estate agent is found in the walk-in closet of Mark's sister's new house. Mark and Steve have to work around Dora Sloan's annoying habits while investigating the murder.

Dr. Sloan takes in an abandoned young girl found at the scene of a murder, while Steve and Jesse go about tracking down the killer.

One police officer is accidentally shot by another during a raid gone wrong. Dr. Sloan investigates the victim's wife, the shooter, and a conniving lawyer when he suspects foul play.

A devious psychologist uses hypnotism to facilitate his criminal acts, including the murder of his wife.

Steve becomes embroiled in political intrigue after the murder of a city councilman's wife appears to be part of a larger political strategy. Steve investigates two mayoral candidates, the councilman and the chief of police, as well as a rogue detective and his partner, all with strong motives.

Mark, Jesse, and Amanda are trapped in a hotel when it's quarantined after a deadly virus is released. They struggle to contain the virus, while at the same time trying to locate its origin. Meanwhile, a scheming seductress carries out her plan, using the virus as a diversion to rob a nearby bank vault.

Steve teams with a Naval Investigator when the apparent suicide of a military officer turns into a cold-blooded murder.