Tony Lip, a bouncer in 1962, is hired to drive pianist Don Shirley on a tour through the Deep South in the days when African Americans, forced to find alternate accommodations and services due to segregation laws below the Mason-Dixon Line, relied on a guide called The Negro Motorist Green Book.

After bowler Roy Munson swindles the wrong crowd and is left with a hook for a hand, he settles into impoverished obscurity. That is, until he uncovers the next big thing: an Amish kid named Ishmael. So, the corrupt and the hopelessly naive hit the circuit intent on settling an old score with Big Ern.