On the run in the year 1987, an Autobot scout known as B-127 seeks refuge in a junkyard in a small Californian beach town. After a brutal battle on his home planet of Cybertron against the Decepticons, the weakened Autobot takes the form of a yellow Volkswagen Beetle to hide from any pursuing enemies. His silence is self-imposed, as his voice box was damaged during the conflict. Meanwhile, struggling with the loss of her father and feeling out of place in her life, a teenage girl named Charlie Watson stumbles upon the battered and broken Beetle while scavenging for car parts on her 18th birthday in hopes of fixing up a vehicle of her own.

Charlie's excitement over her discovery quickly turns to amazement when the Beetle unexpectedly transforms into the alien robot, B-127. Despite the initial shock, the curious and mechanically inclined teenager befriends the Autobot, whom she nicknames Bumblebee, discovering his playful personality and extraordinary capabilities. They soon develop a close bond, with Charlie helping Bumblebee to recover from his injuries. However, their friendship is threatened by the arrival of a government agency known as Sector 7, led by Agent Burns, who is determined to hunt down and capture Bumblebee following prior encounters with Transformers. Unbeknownst to them, the danger increases as two Decepticon trackers have arrived on Earth and are closing in on their position, intent on eliminating the Autobot scout.