The back story is great: Steve Stein, collegiate dope-dealer-turned-suit at the Doyle Dane Bernbach ad agency, enters a hip-hop-remix contest with a pal in 1983 and smokes the competition. His entry, The Payoff Mix, is a funky train wreck of uncleared samples — the Supremes, Little Richard, Culture Club, Humphrey Bogart — crosswiring Grandmaster Flash's mixology with the pop tune punch lines of Dickie Goodman's Seventies novelty collage singles. Payoff, included here with its offspring Lesson 2 (James Brown Mix) and Lesson 3 (History of Hip Hop), inspired crate-digging producers from Prince Paul to DJ Shadow to Girl Talk, and permanently raised the bar for rap track makers. Influence aside, what's just as impressive about this handsome anthology of barely legal rarities is how well tracks work as songs. The early party joints build and ebb with intractable momentum, and later pieces tell unlikely stories. "The Motorcade Sped On" samples newscasts on the JFK assassination; the chilling "Number Three on Flight Eleven" documents a flight attendant's 9/11 call for help. And the hilarious, hour-long "Nothing to Fear" megamix proves that this guy didn't just pioneer the mash-up, he's still the outlaw genre's dean.