From junior-high days: Screech is "tried" for pulling a prank on Miss Bliss (Hayley Mills). Dustin Diamond, Mark-Paul Gosselaar.
Sonny's cruel punishment of a lounge singer who wants out of his contract triggers a cascade of events that leads to Vinnie's being photographed with McPike--a photo that is to be delivered to Sonny.
Sonny's impending marriage to a syndicate boss' daughter begins a supposedly businesslike realignment of "families", but Vinnie learns that the wedding is a pretext for a bloody gang war.
An outraged Sonny Steelgrave accuses Vinnie of betraying him to his arch rival, then realizes the devastating truth-- that his paisan is an undercover Federal agent.