Unable to find work after his release from prison, seasoned thief Scott Lang reverts to old habits to make a quick buck. After breaking into a San Francisco mansion and cracking its safe, he is disappointed to only find a suit inside. Little does Scott know, however, that the suit has the power to shrink its wearer whilst maintaining their strength. Soon, he finds himself embarking on a unique mission with the contraption's inventor, Dr Hank Pym, as they team up to attempt a heist that has the fate of the world resting on it.