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 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.

After a priest witnesses the murder of a parishioner, he will have to give up his special vocation in order to enter WITSEC.

Mary uses a thief to catch a thief when she asks a witness to consult on a crime in order to exonerate Brandi of grand theft auto.

Mary's paranoid witness wants to reconnect with his son.

Mary is caught between a witness and a suspect.

A beauty pageant queen finds out that she's spent most of her life in witness protection

Mary works with an unapologetic con artist.

An Amish witness comes into the program and must learn to adapt.

A terminally ill father wants to reconcile with his children.

Mary plays marriage councilor in order to mediate a WITSEC divorce. Not only must she reconcile a stubborn witness, but also thousands of years of Hindu tradition, in order to save the case and keep a family out of danger.

Mary gets a WITSEC two-fer, when a witness is forced to enter the program after being mistaken for his "evil" twin brother. Not only must she protect the pair from their enemies, but also from each other.

Marshall and Stan contend with a rock-star witness and her controlling mother while Mary is away on a WITSEC-mandated road trip.