Rose plans a surprise birthday part for Michael. Tommy decides to play dirty to be the majority leader.

A hit is ordered on Michael. Marty Trio works with the FBI to get Freddie by wearing a wire. Declan thinks his partner might be a dirty cop.

Tommy outmaneuvers U.S. Attorney Ellis Franklin as he and Eileen struggle to keep up the appearance of a happy marriage. Michael, who has no memory of his attacker at the wedding, tries to re-establish his territory with Freddie and asks Declan to investigate the source of his head injury. Declan spirals out of control as he finds himself shut out at work and at home.

As Tommy begins his re-election campaign, he turns to his sister, Mary-Kate, rather than Eileen for support. Colin Carr, Tommy and Michael’s estranged Irish cousin, returns to Providence – an event Rose views with deep distrust. Michael and Moe team up for a truck heist while Declan and Cassie have dinner with Cassie’s parents.

Colin helps Michael and Eileen cope with the unexpected death of a friend while Freddie tries to avoid a war with the Italians; Tommy helps smooth things over with the Speaker of the House's mistress.

Rose causes problems between Tommy and Michael. Michael messes up Tommy's real estate deal. Freddie asks Declan for some help. Tommy and Dana get closer.

Tommy doesn't get support from the usual places while struggling to stay on track. Michal looks to make some changes in his life. Colin searches for his father. Freddie asks Declan for help in finding someone.

Michael goes after more power while he and Kath get ready for their little addition to the family. Tommy tries to fix the problems in a bad area of The Hill. Eileen learns from other politicians wives.

Declan gets a new assignment from the FBI. Eileen is in for a shock when she becomes a volunteer at social services. Tommy is feeling pressure to become Judd's replacement as chairman of a committee. Michael and Collin enter a partnership with Nozzoli.

It's Thanksgiving and Rose is fed up with everyone. She leaves and they are forced to figure things out on their own. Freddy and Marty Trio use some information to get a holiday furlough from prison.

Unhappy being the speaker's lackey, Tommy explores the possibility of leaving politics. Rose's birthday party attracts both of her feuding sons. Declan is offered an opportunity to investigate government corruption.

A fire in an abandoned mill that kills several Latino squatters and a firefighter causes political fallout for Tommy. Colin begins drinking heavily because of a love triangle. Declan's investigation bears fruit and is expanded.

Over Labor Day Weekend Tommy, Eileen and the family spend the holiday at a water front property where Tommy surprises Eileen with his plans for their new home away from the hill, his mom and Michael but Eileen won't let her self believe it until it happens. An incident at Nozzoli's barbeque pushes Michael's growing paranoia into overdrive. The absence of Kath and Colin who have gone away together does little to ease his mind. Declan and Cassie get away for a romantic weekend, which is ruined by their past marital difficulties.

Declan's investigation triggers alarms among the corrupt politicians so Tommy tries to finesse information from the investigation. Rose receives a diagnosis and shares the truth with Ellen. Michael and Colin begin to clash as they help Freddie plan a robbery.

Tommy's plan to extricate himself from political entanglements hits a snag when Speaker Danatello seeks his help passing the budget. Declan learns more about Tommy's involvement in the Waterfront Project and connects Tommy to Nozzoli. Michael's jealousy over his mother's attachment to Colin adds fuel to his paranoia about Colin and Kath.

Michael returns to Kath but she and Colin begin to worry as the FBI fuels Michael's suspicions about their relationship. Eileen is confined to bed rest for the duration of her pregnancy. Tommy seeks Michael's assistance as Declan begins to zero his investigation in on the Waterfront Project.

Tommy becomes heir apparent for Speaker when Donatello's condition worsens; Freddie maneuvers to get on Tommy's good side; with the mob, the state police, and feds after him, Michael's obsession with Colin puts everyone in jeopardy.