The fifth season of The Sopranos introduced a string of brand new characters including Tony's cousin Tony Blundetto, who along with other mafiosos is released from prison. Among the others released are former DiMeo Crime Family capo Michele "Feech" La Manna, Lupertazzi family capo Phil Leotardo, and semi-retired Lupertazzi consigliere Angelo Garepe. Tony offers Tony B. a job, but he respectfully declines, as he is determined to lead a straight life. He initially begins to take courses to earn a degree in massage therapy and aspires to open up his own massage parlor. After Carmine Lupertazzi dies of a stroke, his death leaves a vacancy for boss of the Lupertazzi Family, which will soon be fought over by underboss Johnny Sack and Carmine's son Carmine Lupertazzi, Jr.. After Feech proves to be an insubordinate presence, Tony arranges for him to be sent back to prison by setting him up with stolen property, violating his parole.
Tony, now separated from Carmela, takes a romantic interest in Dr. Melfi. Carmela is forced to call Tony for help when a wild bear keeps visiting their home. Johnny Sack sees an opportunity for advancement when Carmine suffers a stroke, while new parolees readjust to life on the outside and Janice adjusts to married life with Bobby. Christopher and Paulie face off when Christopher is constantly stuck paying for dinner.
Tony throws a welcome-home party for his cousin, Tony Blundetto, who is released from prison on parole. The FBI continues to pressure Adriana for information and she nearly confesses at Carmela's film club. Carmine's passing leaves the field wide open for Johnny Sack, but Little Carmine has ideas of his own. Tony smells yet another rat and leaves a clear message for the Feds.
Feech begins to overstep when he moves in on Paulie's landscaping deals. Tony worries about Junior's mind when Junior wanders around his old neighborhood searching for long-dead friends. As the hostility in New York intensifies, Johnny Sack dispatches the Leotardo brothers to send Little Carmine a clear message.
Tony and Carmela quarrel after A.J. spends a wild night in the Big Apple. Tony is forced to make a decision about Feech when he continues to overstep his bounds. Carmela finds a romantic interest in A.J.'s guidance counselor, while the war in New York claims its first two casualties.
Tony's intense new feelings for Adriana sends him back to Dr. Melfi; Tony may have skin cancer; While Christopher is on a business trip, the crew discusses a rumor involving Adriana.
Tony B. makes an honest effort to go straight as he prepares to open his own massage studio, but a mysterious bag of money tempts him back to his old habits. A.J. moves back in with his mother after a fight with Tony, while Carmela pursues her relationship with her son's guidance counselor.
Tony pays a visit to his father's gravesite and meets a woman who claims to be his father's mistress. Tony forges a relationship with her as he learns more about his past. Christopher takes a friend from rehab to the executive poker game, but he soon goes from sponsor to strong-arm man when his friend can't pay his debts.
Carmela invites Tony to participate in her father's surprise birthday party, and the evening ends in a romantic encounter. Two of Little Carmine's men try to recruit Tony B. for a retaliation against Johnny Sack's crew. Tony B. is reluctant, but his boredom soon gets the better of him.
Rumors about Tony B's involvement in the Joey Peeps hit reach Johnny Sack, who considers going to war with little Carmine. Meadow looks out for her boyfriend's financial well-being and turns up the pressure on him when their relationship stalls. Carmela finds that Tony has made it impossible for her to hire a divorce lawyer, while Tony explores his guilt over his cousin's incarceration with Melfi.
Janice attacks a mother during her stepdaughter's soccer game and is forced to attend anger management classes. Tony must deal with his own anger as Johnny Sack launches payback against the Sopranos. Christopher and Tony B. overcome their differences when they are sent to dispose of several incriminating corpses buried in the country.
Tony escapes to the Plaza Hotel for a night of rest and relaxation, but his dreams are haunted by past faces. Another casualty falls in the war between Johnny Sack and Little Carmine, and Tony B. heads to New York for revenge.
The FBI finds new evidence that they use as leverage against Adriana. Adriana relents and tries to persuade Christopher to go into witness protection with her. Tony and Carmela meet over lunch and work toward a reconciliation, which includes a new real estate project for Carmela. Johnny Sack delivers a stern ultimatum to Tony, who is hesitant to give up his cousin.
Tony faces pressure from his own crew to give up his cousin to Johnny Sack. Tony does some soul-searching on Melfi's couch and finally decides on a course of action. A.J. proves himself to be a schemer, while Christopher tells Carmela that he and Adriana have ended their relationship. Tony meets with Johnny Sack to restore peace between Jersey and New York, but the Feds play a surprise card that sends Tony fleeing to safety.