On the run from the mob, Bridget assumes the identity of her deceased twin sister, Siobhan, only to realize that her sister's life was no less complicated than hers.

Bridget discovers a possible clue that could lead to Siobhan's killer, and uncovers intriguing information about Andrew. Machado continues to pursue Bridget. Henry and Gemma butt heads over their investment in Andrew's hedge fund.

Bridget, who's still posing as Siobhan, heads to the Hamptons with Andrew, Gemma and Henry to celebrate Siobhan's birthday. While there, Henry is adamant about rekindling his affair with Siobhan. In other events, Gemma learns some unsettling news and Bridget is forced to reveal some of her past when Machado closes in on some new information.

Gemma reacts angrily to Bridget's revelation, and threatens to expose Bridget unless she exposes Henry's infidelity. Things get worse from there. Bridget goes to an Narcotics Anonymous meeting and does not give her name. "Siobhan" apologizes to Juliet for "stealing" her dad from her mom, and they begin to reconcile.

Bridget can't connect with Gemma, causing her to wonder if something occurred between Gemma and Henry. Juliet's teacher comes to her aid when she stands up to a bully at her new school. Bridget asks Charlie for a favor. Machado investigates Malcolm's disappearance.

Siobhan-Bridget reveals that she has a twin to Andrew and Henry. Henry becomes a suspect in the disappearance of Gemma. Juliet parties to dangerous extremes. Malcolm escapes.

Andrew and Bridget receive upsetting news that also impacts Henry. Juliet and Mr. Carpenter continue to form an unlikely bond. Malcolm arrives in New York and is confronted by Machado. Siobhan's relationship with Tyler is threatened.

Bridget realizes she's growing fond of Andrew. Henry and Andrew's business partner bond. Malcolm has doubts about Bridget's new NA sponsor. Bridget decides to meet Siobhan's therapist in order to gain insight into her sister's life.

Henry homes in on a suspect in Gemma's disappearance. Malcolm goes to the police with his hunch about Charlie. Juliet becomes obsessed with Mr. Carpenter. Machado meets with an informant in Wyoming.

Bridget offers to host a fund-raiser for Juliet's school and learns that her friend Greer knows one of Siobhan's secrets. Siobhan can't believe that Bridget has adapted as well as she has to her new life. Malcolm goes to work for Andrew. Henry mourns his wife.

Juliet's mother visits and causes trouble for Andrew and Bridget. Bridget discovers someone she believes is key to learning more about her sister. Henry finds a lead that causes Machado to think he's closing in on Bridget.

Bridget retraces Siobhan's last steps prior to her disappearance and discovers that her twin kept a secret office. Olivia blackmails Henry into introducing her to Gemma's wealthy father. Tyler faces a moral decision that could impact Siobhan and Andrew.

Bridget encounters someone who played an important role in her and Siobhan's past. Malcolm discovers something of Bridget's in Henry's possession. Catherine asks Andrew to make a decision about Juliet that could have major ramifications.

Bridget realizes she's in over her head when Andrew proposes again. Olivia becomes suspicious of Malcolm. Juliet makes a decision that doesn't sit well with her mother.

Machado's past with stripper Shaylene Briggs is revealed. Siobhan masquerades as Bridget to Malcolm. Henry realizes that Bridget knows more than she should. Tyler takes something from Siobhan that's a key piece of evidence in her revenge plot.

Bridget's search for a missing Malcolm leads her to his hotel, where security footage shows that Andrew was the last person to see him before the disappearance. Meanwhile, Juliet links the attack on Tessa to someone in her family; and Siobhan explains to Henry why she faked her death.

An attempt is made on Bridget's life. As Machado investigates, Henry accuses Siobhan of putting out a hit on her sister while Bridget believes Olivia is responsible. In other events, Andrew admits he asked Malcolm to leave, and Juliet goes missing.

Bridget decides to testify against Bodaway Macawi; Machado is suspended from the FBI. Henry gives Siobhan an ultimatum: give up the revenge plot or they're through.

Bridget, as Siobhan, tells Machado about the attempt on her life and who she suspects was behind it. Bridget accuses Henry of Tyler's murder unaware that Siobhan is listening in. A desperate Catherine takes extreme measures to get closer to Andrew.

Catherine's plot to drive apart Andrew and Bridget falters. Machado learns who wanted Siobhan dead. Siobhan's plan to help Henry hits a snag.

As the vow renewal nears, Bridget realizes she first needs to tell Andrew the truth about who she really is. Meanwhile, just as Bodaway Macawi starts to close in on Bridget, Agent Machado is forced off the case and Henry decides whether he should tell Bridget the truth about Siobhan.