Vince Majestyk is a farmer, and a former U.S. Army Ranger instructor and Vietnam War veteran, who owns and operates a watermelon farm in rural Colorado.

A small-time hood, Bobby Kopas, attempts to coerce Majestyk into a protection racket of using unskilled drunks to harvest his watermelon crop.

Majestyk runs him off with Kopas' own shotgun and hires experienced Mexican migrant workers, including Nancy Chavez, a crop picker who is also a union leader.

In jail, Majestyk meets and annoys Frank Renda, a notorious mob hit man being transferred to a higher-security prison.

He arranges for Kopas to drop the assault charges against Majestyk, and orders his men to find the "melon picker" so he can have the satisfaction of killing him personally.

The next day, Kopas badly injures Majestyk's foreman Larry Mendoza, as he tries to deliver a load of melons, putting him in the hospital.

Howard Thompson of The New York Times said, "Except for some dutiful splattering of gore, it ticks along rather steadily, under Richard Fleischer's unruffled direction.

"[2] The scene in which Nancy and Majestyk drive away in a pickup truck with Renda's men in hot pursuit became one of the most famous chase sequences of the period, following the recent trend of those in Bullitt (1968) and The French Connection (1971).