The plot centers around a hidden event from Earth's past that threatens to ignite a war so large that the Transformers alone will not be able to save humanity. The Autobots, led by Optimus Prime, learn of a Cybertronian spacecraft hidden on the moon, carrying a powerful secret. This discovery sparks a treacherous race against time as the Autobots must reach the spacecraft and unlock its mysteries before the malevolent Decepticons do. The situation becomes more critical when it’s apparent that the hidden secrets could turn the tide in the Transformers' final battle and have dire consequences for Earth.

On Earth, Sam Witwicky, now out of college, is struggling with his own place in life as he tries to make his mark while remaining relevant in a conflict involving otherworldly beings. His relationship with his new girlfriend, who is drawn into the perilous situation, complicates his efforts. As the Autobots unravel the truth of the spacecraft on the moon, they enlist Sam's help once again to aid their cause against the looming Decepticon threat. With the backdrop of an epic space discovery and the fate of Earth hanging in the balance, Sam and the Autobots must navigate a dangerous web of intrigue, mayhem, and betrayal to save mankind from annihilation.