In the first episode we meet Mary Shannon a US Marshall for the Witness Protection Program. In this episode Mary tries to figure out what went wrong when a mobster's son who was under her protection is killed.

The family regroups after Mary's ordeal; Stan and Marshall search for a way to force Spanky to tell the truth about Chuck's drug trafficking; the FBI corners Mary in her driveway with Brandi's suitcase full of meth in the back of her car. Season 1 Finale

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

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

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.

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.

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 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.

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.

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.

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

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

A former high line thief from Boston tries to give up crime for the sake of his teenage son, and Mary and Marshall search for the person who nearly killed Mary.

In 2003 Mary meets Marshall for the first time as they get lovers CLAUDIA TOBIN and HENRY DOER into the WitSec program, and it's a toss-up whose relationship is going to last: Claudia and Henry's, or Mary and Marshall's.

ATF agent Wade Guthrie is shot and left for dead by gun trader Jasper Malone. After three years in a coma, he wakes to find the world he left behind has drastically changed.

Mary and Marshall try to help FBI Agent Mike Faber convince his informant to enter WITSEC. Despite their best efforts, the informant refuses their protection and gets himself into a heap of trouble. After Mary, Marshall and Agent Faber save the informant from certain death, he and his family join Witsec.

Mary’s new witness falls in love for the first time; Mary must stop her witness from taking out his pain in the form of an explosive device.

Mary tries to help a parolee acclimate to life outside of prison after having spent 38 years behind bars while Marshall helps out when one of Mary's witnesses no longer wants to work with her.

Mary's new witness is part of a mortgage fraud ring and is an important link in the case of FBI Agent Faber.

Marshall is being evaluated in the field by his father (Geoff Pierson) during a joint fugitive operation. Mary meets Brandi's secret friend.

A woman wants to escape from her family, who are heavily involved in organized crime, but a secret from her past puts her eligibility for the Witness Protection program in jeopardy.

A witness with Aspergers who has no social filter and can't lie stymies Mary, particularly when the witness refuses to testify against her only friend – the key conspirator in a numbers case. Meanwhile, Marshall and Stan race to figure out why an Immigration and Customs Enforcement agent is holding up the visa of a key witness before she is deported. Plus, Brandi reveals her plan for the money she made by investing with Scott.

Mary helps her latest witness, a homeless man who's struggling with the program, find his birth parents. But the search could cause more problems than she anticipated. Elsewhere, Scott asks to borrow more money, raising a red flag for Brandi.

Mary keeps an eye on a teen witness whose separated parents are too distracted by their own issues to pay attention to their daughter. Marshall thinks a witness may have betrayed his brother; and Brandi tends to Scott after he's attacked.