To take down South Boston's Irish Mafia, the police send in one of their own to infiltrate the underworld, not realizing the syndicate has done likewise. While an undercover cop curries favor with the mob kingpin, a career criminal rises through the police ranks. But both sides soon discover there's a mole among them.

God has abandoned Heaven. It's 1985: the Reagans are in the White House and Death swings the scythe of AIDS. In Manhattan, Prior Walter tells Louis, his lover of four years, he's ill; Louis leaves but as disease and loneliness ravage Prior, guilt invades Louis. Joe Pitt, a Mormon Republican attorney, is pushed by right-wing fixer Roy Cohn toward a job at the Justice Department. Pitt and Cohn are closeted: Pitt, out of shame and religious turmoil; Cohn, to preserve his power and access. Pitt's wife Harper is strung out on Valium, aching to escape a sexless marriage. An angel invites Prior to be a prophet in death.

Kelly's grandpa invites the whole gang to his little hotel "The Hideaway" in Hawaii for summer vacation. They expect a marvelous time at the beach - without Belding. Upon arriving, they quickly learn that not only is Belding there, but they also have to help Kelly's grandpa from losing his hotel. Meanwhile Zack meets (again) the love of his life, Jessie and Slater bet with Lisa that they won't fight, and Screech gets kidnapped by the Pupuku clan.

Drea, a 20-something woman living in Brooklyn, struggles to make progress in her own life while being the sole caregiver for her father, who has Alzheimer's.