D. Sloan is terribly nervous about an IRS audit, sees 'sloppiness' everywhere, and leaves a 'death threat' on his accountant Ernie Pitt's answering machine, desperate for help. When Mark sneaks out from Agent Gretchen McCord's first interview for a 'medical emergency' he thus ends up bent over Pitt's corpse, stabbed to death. LAPD Detective Claire Van Sickle grants him no favors as colleague Steve stood her up a while ago. The two harpies team up to 'coordinate their attack' on Mark.

《谋杀》第二季于4月1日回归，杀害Rosie的凶手也将在第二季浮出水面。翻拍自大获成功的丹麦电视剧《Forbrydelsen》，讲述的是一个发生在西雅图的少女谋杀…

The day Dr. Mark Sloane is to be 'honored' as Man of the Year at the Roast, where comedians makes merciless fun of him in the Jokers Club, which despite its fun-loving name is also a cesspit of envy and blame, Andy Baxter, a sideman who made a surprise appearance grossly insulting the speaker, Lou Summers, and dropping trou he's killed during a very short power break by a knife in the back. While Steve is conducting first interrogations, the killer knocks out Jesse and stabs Lou to death. The crowd provide multiple clues and suspicions, but Mark figures it all out by elimination on accounts of motive and opportunity.

Steven and fellow LAPD Detectives Halloran and Stang (who are partners) find Councilman Watson ( whom they wanted to question about corruption) passed out at home on tranquilizers Mark prescribed; in the next room is his separated wife Janet's corpse. She has been shot and her blood is all over the house. Police Chief Masters, a political rival for the mayoral campaign, refuses to comment. Mark decides to look into Watson's claim to have been framed, working together with Captain Cynthia Pike; even though it may make Steve look bad, he is happy to collaborate. Amanda hopes to work trough her an 'amicable' divorce from baby CJ's dad by becoming a medical examiner in the coroner's office but she finds nothing; this “negative“ finding is enough for Mark to prove there was a frame, and that Stang had motive and opportunity - he shoots himself; his gun was used for Janet's murder. Now Mark sleuths on; Stang could have been framed himself if Masters is in the plot.

During a SWAT bust, Steve's LAPD friend Douglas Quinten 'Doug' Vogel gets killed by a bullet from his own commander, Max Jupe, who is two years from retirement. City Attorney Andrew Chivers forbids Max any contact with the widow Janine, who quickly accepts the 20% profit-sharing legal services of slick attorney Daniel Brent. Actually. Max and Janine were secret lovers who planned Doug's death. Mark quickly catches on when Max is diagnosed with chickenpox, a recent problem in Janine's daycare center, although the lovers claim not to have met in three months. A 'shooting demonstration' by cocky Max proves that he doesn't need glasses and he is a superb marksman. Janine takes another lover-her lawyer Brent, who is suing Max and the city for $10 million.

Teenager Ashley York murders her sick father Arthur by fixing his Deprosine pills to an overdose. Mark doesn't believe it's suicide, there's no note, absolutely no fingerprints and he set the coffee machine timer for after his death; Jesse concurs his intake of other medicines makes no sense for a suicide. Amanda shows Jesse a postcard: his predecessor Jack Stewart has set up a fancy private practice after his residency in Community General. Then Ashley, who overheard the Sloans, 'finds' a note, but computer-printed, and as Mark soon proves posthumously, murder. Ashley's mother, Dr. Elaine York, intends to keep the purse strings of her $7,000,000 trust-fund till she turns 25. Jesse finds out via a financial friend that Elaine, as a doctor certainly capable of the murderous plan, paid Arthur $2,000,000 at their divorce and kept paying the expensive beach-house, while his entire estate goes to Ashly.

Mark Sloan is a doctor at Community General Hospital, and he is a consultant for the police department. His son Steve Sloan is a detective for the department. He and his father, along with emergency room resident Dr. Jesse Travis and Dr. Amanda Bentley, who is the pathologist at the hospital help to solve some very strange murder cases in Diagnosis Murder

Caitlin Sweeney bombed Community General in the last episode, and a number of characters are trapped in the rubble. Mark worked hard to save Amanda's life. After 4 months pass, the hospital starts to reopen, and Steve announces that Caitlin has started robbing banks to raise money for R.O.A.R.: Revolutionary Order for Armed Rebellion. Steve and Jesse discuss plans to buy Barbecue Bob's, which is going out of business.

在前往杰玛（Gemma）和特里（Terry）婚礼的路上，杰玛将众人带至一家夫妻治疗静修所去解开一个谜团，该静修所收到了死亡威胁。随着死亡人数不断增加，那些不同寻常的治疗方法让他们的关系变得紧张起来。

《谋杀主谋》第二季将于7月17日周日回归Oxygen True Crime频道。在这部不容错过的一小时长的系列剧集中，调查人员找出凶手后，案件并非就此简单了结。相反，这些谋杀谜团会有两个揭秘时刻：一是谁开了枪，二是谁是这一切背后的主谋。每一集都会调查一起针对毫无防备之人的谋杀案……