Wade Wilson, a former Special Forces operative moonlighting as a mercenary in New York City, meets an named Vanessa at a local bar.
What begins as a one-night stand blossoms into a relationship, and after a year Wilson proposes to Vanessa. Shortly after she accepts, Wilson is diagnosed with terminal cancer. While Vanessa remains loyal, Wilson abandons her, not wanting her to see him wither and die.
Agent Smith, a recruiter from a covert organization, approaches Wilson with the opportunity to become a superhero, promising abilities that will cure Wilson’s cancer. Wilson accepts the offer and is taken to a remote laboratory where he meets Ajax and Angel Dust. Ajax injects a mutation-activating serum into Wilson and subjects him to daily torture to prompt a mutation.
Annoyed with the lack of results and Wilson’s defiant attitude, Ajax seals him to an oxygen chamber, which periodically asphyxiates and resuscitates him. Wilson develops an accelerated healing ability, but suffers burn-like scars over the entirety of his body. Ajax reveals to Wilson the true purpose of the laboratory is to create mutants to sell to wealthy clients as slaves. Wilson escapes and battles Ajax, who mocks Wilson with promises of curing his disfigurement, before escaping.