Torello's team must protect a US Senator, the head of the Senate subcommittee that will investigates the mob, a glamorous actress, who wants to cut her ties to the mob, and a lusty, sleazy politician with a serious gambling addiction.
Torello's ex is in Vegas with her new man. When they were at a robbery he is taken by the robbers. When she sees the local police are not doing anything, she calls Torello who clashes with the cop in charge.
The Senterros, a family of Mexican cattle ranchers, controls the marijuana trade, so Torello's unit sets up a sting operation, but detective Joey Indelli leaves to try to save a callgirl from her sadistic pimp.
Torello's ordered by the government to leave Luca alone, since he's now their asset. Abrams quits his job immediately in disgust. Luca's former associates start to fear for their future in the crime business.
Torello's having a birthday party in a restaurant. His best friend and partner Sgt. Danny Krychek is shot in the bathroom. He whispers a clue to who the shooter is and heads for surgery. Mike must beat the clock to catch the assassin.
A man hires a private detective to find his girlfriend, who turns out to be the daughter of a mobster. Things don't go well. Meanwhile, Abrams has become an addict, so sympathetic Torello offers him a place in his team.
A Russian pilot defects by flying his plane into the U.S. and landing in Nevada. Torello and his men are assigned to protect him. They become friends. But Torello learns that the government is considering trading him for the U2 pilot being held in the Soviet Union. And they try to stop it from happening. Abrams who now works for Luca helps him get something on a guy whose business he wants to buy.
Torello helps a pretty Asian girl find her missing father, who's been owing money to some loan sharks. What he doesn't know is that she's actually a secret agent of communist China on a radioactive mission.
How Paulie and Luca survived the atomic blast that seemingly killed them both at the end of season 1, how they made a deal with the government and how, with a little help from their mob friends, they got back in the business.
Torello and his crew are after Luca, so he hides in Mexico. They go after him, even though the US government refuses to help them track him down there. However, this time Torello has a contact there who can help.
Danny ends up in Mexican prison. Torello manages to fins allies among mobsters who hate Luca, to get Danny out before he gets shanked. Luca demands respect from a corrupt local general, but he gets none.
Luca gets hold of Abrams and forces Torello to give him back his captured heroin shipment in exchange. However, Mike's not going to let him escape this time and goes after him anyway, with tragic consequences all around.