Upon his release from prison, well-meaning thief Scott Lang moves in with his old cellmate, Luis. While visiting his daughter Cassieunannounced, Lang is rebuked by his former wife Maggie and her police-detective fiancé, Paxton, for not providing child support. Unable to hold a job because of his criminal record, Lang agrees to join Luis’ crew and commit a burglary. Lang breaks into a house and cracks its safe, but only finds what he believes to be an old motorcycle suit, which he takes home. After trying the suit on, Lang accidentally shrinks himself to the size of an insect. Terrified by the experience, he returns the suit to the house, but is arrested on the way out. Pym, the homeowner, visits Lang in jail and smuggles the suit into his cell to help him break out.