On the run in the year 1987, Bumblebee finds refuge in a junkyard in a small Californian beach town. Charlie, on the cusp of turning 18 and trying to find her place in the world, discovers Bumblebee, battle-scarred and broken. When Charlie revives him, she quickly learns this is no ordinary yellow VW bug.

Just when his time under house arrest is about to end, Scott Lang once again puts his freedom at risk to help Hope van Dyne and Dr. Hank Pym dive into the quantum realm and try to accomplish, against time and any chance of success, a very dangerous rescue mission.