The plot centers on the implacable and remorseless Walker (Lee Marvin, Parker in the novel), who is double-crossed and abandoned by his friend, Reese (John Vernon's first major role). After taking all the cash robbed from a courier in a large gambling operation, Reese shoots his partner Walker and leaves him for dead.
In a double-double-cross, Reese also makes off with Walker's wife, (Sharon Acker). Afterward, Walker sets out to recover his lost money, chasing Reese - now a member of the corporate crime syndicate, The Organization. Walker sees no difference in the two, and pursues Reese and his superiors in a series of confrontations with The Organization, which has acquired all the trappings of a corporation, including accountants and currency-free financial transactions.
Completely baffled by Walker's fearless and single-minded determination to get both revenge and his share of the loot from Reese's new employer, The Organization is slow to react and underestimates its new adversary, an error that soon proves fatal
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