Tommy Caffee is a rising star in Rhode Island politics and the prince of his home ward - a working-class Irish district known as "The Hill." The murder of local gangster Patty Mullin opens the door to the return of Tommy's brother, Michael, whom Patty had sworn to kill. As Michael begins to reclaim his lost criminal enterprises, Irish mob boss Freddie Cork threatens to whack Michael unless Tommy throws state contracts Freddie's way. Meanwhile, Michael gets into a beef with Moe Riley, one of Freddie Cork's underlings, who is currently in control of Michael's old turf. Eileen Caffee, Tommy's wife, has secrets of her own: she meets Carl, an old boyfriend, at a local motel, where they smoke dope and have sex. In the end, Michael achieves a tenuous treaty with Freddie.
Michael plays a game of Russian roulette with the mentally challenged brother of a neighborhood store he wants to take over. Meanwhile, Tommy is working on keeping a highway spur from going through the hill by wheeling and dealing behind the scenes. Also, Eileen gets some upsetting news at the doctor's office when she learns that she has contracted a sexually transmitted disease resulting from her secret tryst.
When Freddie Cork refuses to let Michael and Pete play on his softball team in a local bar tournament, Michael enlists the aid of bar owner Terry Mulligan. Rose loses a fight to stop layoffs within her factory and is fired as well. When the Speaker proposes a new waste-disposal station in his district, Tommy tries to make sure his constituents are properly compensated.
Michael convinces Tommy to help save a local movie theatre. Eileen confesses to Mary-Kate. Rose is forced to take a job at a big box store. Pete falls off the wagon. Declan finds out something about Marty Trio.
As Tommy begins his reelection campaign, he turns to his sister, Mary-Kate, rather than Eileen for support; Colin Carr (Brian F. O'Byrne), Tommy and Michael's estranged Irish cousin whom Rose deeply distrusts, returns to Providence.
Tommy strong-arms the mayor for his support of a development deal, but hits a roadblock due to Michael's business dealings; Rose investigates her mysterious ailment; Eileen is passed over for promotion due to her pregnancy.
A fire kills several Latino squatters and a firefighter, leaving Tommy struggling with the political fallout; Colin's torch for Michael's girlfriend Kath begins to affect his work; Declan uncovers a lead and brings in another investigator.
The Labor Day holiday weekend finds Michael increasingly paranoid and edgy; Tommy proposes a radical lifestyle change to Eileen; Declan and Cassie's getaway highlights the growing problems in their rocky marriage.
Eileen worries that her family will never leave The Hill when Speaker Donatello draws Tommy back in to help pass the budget; Declan tries to link Tommy with Nozzoli; Rose's attachment to Colin fuels Michael's anger and paranoia.
Kath and Colin worry about what Michael might be capable of if he becomes too suspicious of their relationship; Eileen goes stir crazy when her pregnancy confines her to bed; Tommy asks for Michael's help with the Waterfront investigation.
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.