Young adult orphan comic-illustrator Steve Ashburn's life-threatening disease requires super rare "Bombay" blood type. When his only New York donor bails out, his obsessively devoted big sister, Wall Street broker Jessica Ashburn, finds out it's illegal Colombian Alejandro, and bribes him to resume donating if she helps him avoid deportation, which proves possible only by fake marriage. Hedonistic Alejandro infuriates her, but immigration is on the case, and overprotected Steven soon takes to him like a cool big brother. Jessica's fiance and superior, Paul Heiser, wants Alejandro deported, needing marital witnessing protection as Jessica's spouse to cover up his illegal deals. Alejandro handles the officials brilliantly, even after Jessica throws him out, and takes Steve back into 'knavish life', even 'medicinal' weed, which alas leads to a scary fall. Jessica is last to appreciate him truly.