Snapfiles

Plot[edit]

In 484 AD, King Arthur and his knights struggle in a battle against the Saxons. Meanwhile, Merlin begs for help from the Knights of Iacon, a group of twelve Transformers who have hidden on Earth. They give Merlin an alien staff and combine themselves into a huge dragon to help Arthur triumph over the Saxons, but not before warning Merlin that a great evil will one day come for the staff.

In the present, five years after the Hong Kong battle, the Transformers are declared outlaws by all governments on Earth, to which the Transformer Reaction Force (TRF) is formed from the fallen Cemetery Wind to eradicate the alien robots, despite more Transformers continuously arriving on Earth. All the while, enormous metallic horns begin to rise from different parts of the world. In a part of war-torn Chicago, a group of children find a ship with a knight inside before being caught by a TRF drone. Izabella, a survivor of the Battle of Chicago, saves the children along with her Transformers companions Sqweeks and Canopy. The drone mistakes Canopy for a Decepticon and kills him before Bumblebee and Cade Yeager (who are also being hunted by the TRF) arrive and help the children, Izabella, and Sqweeks escape from the drones. While fending off the TRF, Cade finds the knight in the ship, who attaches a talisman to his arm. The Decepticon Barricade observes this act and reports the discovery to Megatron. Cade then returns to his junkyard in South Dakota (with Izabella and Sqweeks hitching a ride with him) where the remaining Autobots are hiding from the TRF, including Bumblebee, Hound, Drift, Crosshairs, Wheelie, Grimlock, Slug, Daytrader, Trench, and three Mini-Dinobots.

In deep space, Optimus Prime crash-lands on Cybertron, discovering that it is heading directly for Earth. He encounters Quintessa, the self-proclaimed creator of the Transformers, who brainwashes Optimus and renames him Nemesis Prime. Quintessa charges him with recovering the staff from the Knights who stole it from her. Earth, she reveals, is actually Cybertron’s ancient enemy Unicron and she intends to drain its life force using the staff, so that Cybertron can be restored.

TRF member and former Autobot ally William Lennox brokers a deal between the TRF and Megatron so he can find Cade and recover the talisman. In exchange, Megatron demands the release of a squad of Decepticons, including Nitro Zeus, Dreadbot, Mohawk, and Onslaught (Megatron tries to get Berserker, but they won't let him because he is far too dangerous). Megatron and the TRF locate Cade, his coworker Jimmy, Izabella, Sqweeks, and the Autobots thanks to a tracker planted on Bumblebee during the fight in Chicago. They flee to an abandoned town where they discover Bumblebee's tracking device. In the ensuing battle, Dreadbot, Onslaught, Mohawk, and several TRF soldiers are killed by Grimlock, Slug, Crosshairs, Drift, and Bumblebee. As a result, Megatron, Nitro Zeus, and Barricade are forced to retreat. While fighting off TRF drones, Cade is approached by Cogman, a Transformer envoy who takes him and Bumblebee to England to meet his master, Sir Edmund Burton. There, Burton arranges a meeting between Cade and Viviane Wembly, an Oxford professor, who had just been kidnapped by the Autobot Hot Rodunder Burton's orders. Burton introduces himself as the last living member of the "Witwiccan" order, an ancient brotherhood dedicated to guarding the secret history of Transformers on Earth. He also reveals that Viviane is Merlin’s last descendant and that she must find and use his staff to prevent the impending destruction of Earth by Cybertron.

After fleeing from the TRF, Barricade, and the police (causing many car accidents along the way), Cade, Viviane, Bumblebee, and Cogman follow the clues left by Viviane’s father and take the museum submarine HMS Alliance (after Burton shuts down the attraction and evicts the tourists) into the sea to find the Cybertronian Knights' sunken ship while the TRF pursue them with submarines of their own. Burton meets with the Prime Minister to engage the military at Stonehenge, which he deduces is the access point to Unicron. In the ship, Cade and Vivian discover the tomb of Merlin and the staff. Viviane activates the staff, and the ship rises to the surface. The TRF confronts the group and attempts to take the staff from them before a mind-controlled Optimus intervenes and forces them to hand over the staff. Bumblebee chases after Optimus and the two Autobots fight each other. Before Optimus can kill Bumblebee, the mute Autobot finally speaks, freeing Optimus from Quintessa’s control. Megatron, revealed to be conspiring with Quintessa and unhappy with Optimus's failure, arrives to steal the staff and flees while the Knights attack Optimus for his presumed betrayal. Cade stops the Knights with the talisman, which transformed into the sword Excalibur, and the Knights yield to Cade as the last Knight. He then urges Optimus to fight for Earth once more.

As Cybertron anchors itself to Earth, Megatron, Nitro Zeus, and Barricade deliver the staff to Quintessa, who begins draining the life force of Earth from Unicron. Burton and the British military intervene, and Megatron shoots Burton, who dies with Cogman at his side. The Autobots arrive to join the fight with the TRF, Cade, Viviane, Izabella, and Sqweeks, landing on Cybertron and battling against Megatron and Quintessa’s minions, the Infernocons. Vanquishing their foes with help from the Knights as the dragon, the Autobots reach the chamber where the staff and Quintessa are. Optimus defeats Megatron by kicking him through the Ignition Chamber's wall, sending him flying to Earth, while Bumblebee kills Nitro Zeus. Together, Optimus and Bumblebee seemingly kill Quintessa. Viviane removes the staff, stopping Cybertron's destruction of Earth but leaving both worlds connected. Optimus declares that humans and Transformers must now work together to rebuild their worlds and sends a message calling any surviving Autobots to come home.

In a mid-credits scene, scientists inspect one of Unicron's horns in a desert. Quintessa, who has survived and is disguised as a human, arrives and offers them a way to destroy Unicron.