Employees include restless cook Stephen (nicknamed "Red Ryder"), mousy waitress Angel, and their no-nonsense boss Clark.
The boring routine of the daily grind is disrupted with the arrival of two couples, the upscale Richard and Clarisse, and the younger and wilder Teddy, an unbalanced Vietnam War vet, and Cheryl, his hippie girlfriend.
Complications arise when illegal drugs and guns enter the picture, and Teddy resorts to physical, mental, and emotional torture when he holds everyone hostage.
Lyle, the gas station attendant across the street, enters and offers to lend Red some money so he can buy a car to leave town.
Teddy, a foreboding man dressed in fatigues, and his much younger girlfriend, Cheryl, enter and tell everyone their car needs a new part.
He comes off as incredibly abrasive as he orders his food and makes small talk, prodding Angel, Red and Richard with increasingly uncomfortable questions, and his threats are often veiled by a joking manner.
Teddy then moves on to Angel, suggesting that her weight and lack of smarts will land her in the same spot for the rest of her life; unmarried and spending her evenings watching TV with Lyle.
He threatens Red with violence if he doesn't pretend to ride around on a horse, "slap leather", and kiss his "best gal", (played by Angel), on the lips.
Teddy himself starts to dance which turns into a frenzy as he rips open Clarisse's shirt and roughly shoves her in front of the men, suggesting they ogle her like they previously did to Cheryl.
Red finally tells him off before accepting Lyle's loan and hitching a ride with Richard and Clarisse to leave the diner, and the town, for good.
Lyle asks Angel if she'll be over to watch TV tonight and she says she should stay home and make amends with her mom.
The 1979 film version of When You Comin' Back, Red Ryder?, adapted by Medoff and directed by Milton Katselas,[3] starred Marjoe Gortner, Candy Clark, Stephanie Faracy,[4] Lee Grant, Hal Linden, Peter Firth, Pat Hingle, Audra Lindley, and Anne Ramsey.