Mary briefs a new witness whose visitation rights with his son depend on the man's testimony. When Mary learns the boy is missing, she tries to find him.

Mary and Marshall find themselves in a difficult position when Stan's very first witness turns up dead and he is implicated in her murder.

The barely legal daughter of Mary's witness – a Miami racketeer – finds herself in a dangerous romance, just as Raph's mother visits to prepare an engagement feast for the surprised Mary.

When a Wall Street blue blood rats on his boss' investment fraud and hides out in WITSEC, something from his past life comes calling.

A witness finds herself having difficulty in managing her own brood of children, so Mary offers to babysit the trio of problem kids.

When a series of murders seem to follow a new ex-con witness, including stabbing Mary's friend, she and Marshall have to figure out if he's the killer in time to save his next victim.

A world-class counterfeiter witness is suspected in a murder; Mary and Marshall realize they may be hiding a witness from the government.

A northern California marijuana mastermind cannot testify without using the drug to neutralize his anxiety disorder.

A dead witness causes Mary to take leave of her administrative duties to solve a "Ten Little Indians" story, until her plan gets changed by her own brand of Post-Traumatic Stress disorder.

FBI agent O'Connor arrests Brandi on charges of drug trafficking and murder. Insisting her sister is innocent, Mary works to help Brandi while ultimately trying to discover O'Connor's real motive for his actions.

Mary lends her expertise for the U.S. Marshalls by making a training video with a film crew. Elsewhere, Marshall prepares the arrangements so that an elderly mobster in Witsec can go to his son's funeral.

The US government helps a Latina political activist hide in Witsec, but the arrangement sours after she moves into her new home.

A building collapses on one of Mary's witnesses, leaving him exposed to outside threats, so Mary has to risk her life in order to keep her witness safe.

An Orthodox Jew enters Witness Protection, but his wife refuses to join him. The situation is made more complicated by the fact he is being pursued by a man motivated by a higher authority.

An engineer blamed for a bridge collapse enters the program after being targeted by angry family members of the victims who died in the tragedy.

Mary and Marshall take on a case involving Horst Vanderhoff, an agent for Lola, who's an assassin for hire. While trying to line up her next job, Horst is busted and agrees to testify against her to become a part of the Witness Protection Program.

Mary learns that her witness, a NCAA basketball star, has a gambling problem

A member of the Program under Mary's watch is in a car accident and Mary has to find out if it was an accident or related to his former life.

Mary suffers the consequences when an attractive witness, who she slept with, is accused of murder.

Natasha, the mild mannered Ukrainian accountant, has gotten her new breasts, but her life becomes more complicated when she discovers that her new boyfriend is also in WITSEC.

After watching her mother audition for "Sweet Charity" Mary is kidnapped; in New Jersey, Brandi's boyfriend Chuck is abducted and two FBI agents are killed; when federal agents suspect a connection, a nationwide manhunt ensues.

Things get complicated when Mary takes on the case of Leo Billups. Leo saw his mother murdered and is going to testify against the people who killed her including his father.

Mary's assignment this week is Treena Morris a con-artist who is married to a diamond smuggler. After she is arrested by the feds, she decides to tell all on her husband and his friends. While Mary is trying to keep her safe, Treena gets engaged and her photo is all over the papers.

Mary works to solve the mystery of who tried to kill her witness, an art dealer. To complicate matters, both his mistress and his wife are in the program…and key suspects.

The closeness of a family is tested when they enter the program after the daughter witnesses a shooting.