Following the destruction of Cybertron's last working Space Bridge, Optimus Prime and his crew aboard the Ark find themselves teleported into interstellar space. However, Optimus's Matrix of Leadership projects a star map, which guides them to the long-lost world of Velocitron, one of the colony worlds that was abandoned millennia ago and left to its own devices. Taking a small group of Autobots, Prime discovers that the planet is still inhabited by a culture of speed-obsessed Cybertronians. Encountering Ransack, a surly co-ruler of the planet, he and his party travel to Delta, the main capital of the planet. There, Optimus sees the full extent of Velocitronian culture—a hyper-specialized lifestyle that has eschewed all other forms of transport besides wheels—and meets Override, the other ruler of the planet, who won her position through a race.
The Velocitronians falsely believe that the Cybertronians have arrived to save them. Override confides in Optimus Prime that their society is gradually collapsing; not only is their sun in its final period of its life, they have been running short on planetary resources for a while. Nevertheless, they are preparing for the great Speedia race to determine the fastest Velocitronian. As he watches the race, Optimus mulls over the fact that these races are similar to the gladiatorial matches that allowed Megatron to begin his rise to power. As a way of showing the Velocitronians that the Autobots are powerful, Optimus orders Silverbolt to fly over the race as it ends (Blurr is the winner), which awes most of the Velocitronians but only angers Ransack.
Eventually, the other Autobots land the Ark at Delta and commence repairs on their ship. Optimus Prime takes advantage of this to explore the world of Velocitron, traveling with a young Velocitronian named Clocker to the remnants of the planet's Space Bridge.
Meanwhile, Ransack and his bodyguard are contacted by another mysterious Cybertronian, who only goes by the name "777". 777 tells them about the coming Decepticons and Megatron, which intrigues Ransack and his group.
Meanwhile, at the Space Bridge, Optimus Prime communes with the Matrix, which shows him a cryptic vision—but, at the same time, allows him to encounter a mysterious piece of metal, which Optimus believes to be a part of the mythical Star Saber. However, the two come under fire from a group of Decepticon sympathizers. Clocker and Optimus manage to escape and return to Delta. However, both Clocker and another Velocitronian mechanic named Mainspring decide to leave with Optimus aboard the Ark.
Upon returning to Delta, Optimus consults with the other Autobots about the meaning of the metal shard. They are interrupted by Blurr, who realizes that the trophy he won at Speedia contains a similar shard. Not long afterwards, the Ark is sabotaged. As the Autobots try to repair it, Ransack strikes with his acolytes, trying to wrest leadership from Override. Override responds in kind, and as the Autobots try to escape from the planet, Velocitron is plunged into civil war.
The Autobots manage to escape, and find themselves in orbit around an even stranger world; a planet of garbage and trash called Junkion. Optimus and a small crew encounters an eccentric bot named Wreck-Gar, who claims to be the leader of the scavenging tribes on the world. His mind temporarily cleared by the power of the Matrix, he and the other Junkions pledge their allegiance to Optimus and vow to help repair the Ark.
Meanwhile, the Nemesis, having also been transported into interstellar space by the Space Bridge, pick up the Ark's trail and make preparations to land on Velocitron, where they believe the Autobots are.
As repairs commence on the Ark, Optimus Prime travels down into the depths of Junkion, discovering a mysterious ship. The Matrix projects another map, directing him to the last of Junkion's functional Space Bridges. Upon reaching the surface, he requests use of a ship from Wreck-Gar. However, Prowl discovers that Shearbolt—a trader that the Autobots encountered early on, had been killed before the Autobots landed, causing Optimus to suspect that there may be a Shifter aboard. At the same time, Axer, an ex-Decepticon stranded on Junkion through a Space Bridge mishap, tries to convince Wreck-Gar to turn against them. While both groups begin scavenging parts to repair a ship, Optimus discovers another mysterious artifact about to be incinerated, but manages to save it at the last second.
Meanwhile, on Velocitron, Override and her cadre of loyalists are visited by an enigmatic group of pirates, who claim to be looking for Cybertronians. Their arrival ignites tensions and causes the civil war to redouble.
Simultaneously, on Junkion, Prowl manages to track and trace Axer, interrogating him about Shearbolt's killing. From his testimony, Optimus Prime and Jazz manage to deduce that Hound is the Decepticon Shifter, and manage to lure him into a trap. He is taken prisoner by the Junkions. Meanwhile, the Nemesis arrives on Velocitron. Megatron encounters several Decepticon-allied Velocitronians, including Ransack, and gains several new followers. However, the Nemesis almost immediately makes preparations to leave for Junkion, in pursuit of the Autobots.
Optimus Prime, Silverbolt, Bumblebee, and Jazz travel through the Space Bridge, reaching a new region of space that contains the tomb of weaponsmith Solus Prime. A hologram of Solus Prime appears and warns Optimus and the others to leave immediately. However, a messenger from Cybertron—a young Autobot named Chaindrive, teleported there by Wheeljack—appears and gives Optimus two more pieces of the artifact, which Optimus realizes are the Blades of Time. Assembling them correctly, he contacts Vector Prime, who informs him about the nature of the Requiem Blaster and its location, which is sought by Axer. Returning to Junkion, the party arrives just in time for the Nemesis to appear, launching an attack on both the Autobots and Junkions.
As the fight rages across Junkion, Axer manages to escape down to the core of Junkion, discovering the Requiem Blaster. However, when he moves it, the gravitational disturbance it creates begins to tear Junkion apart from the inside out. Reporting to Megatron, the Blaster is grafted to the hull of the Nemesis. The disturbances awaken another Junkion named Cannonspring. Cannonspring, Mainspring, Pinion, Clocker, and Chaindrive unite into the mythical Nexus Prime. Nexus contacts Optimus and bestows upon him the Cyber Caliber, a legendary sword. Megatron and Optimus duel atop a bridge, with Optimus ultimately triumphant. However, at that moment, he receives a vision of the Allspark's location, and begins to retreat towards the Ark to pursue it. The Requiem Blaster overheats, and is jettisoned by the Decepticons.
The Star Seekers too arrive on Junkion as part of their quest. Taking Wreck-Gar and many of his Junkions prisoner, they force the natives to weld a Space Bridge to the hull of their ship. Axer is also taken aboard as a hostage, but manages to convince Thundertron, their captain, to keep him alive so that he may lead them to more Cybertronians. The hunt for the Allspark continues, but the Star Seekers are now also in pursuit...
- Star Seekers
- Irvine said that the space bridges will play an important part in the sequel, "and they lead to some unexpected places". The focus remains on Optimus Prime and Megatron, but the original Thirteen Primes and their Artifacts "comes to play in this book too, but in unexpected ways".
- Originally, the title was going to incorporate Prime.
- In chapter three and the start of chapter four, the first team sent down to Velocitron is composed of Prime, Bumblebee, Jazz and Perceptor, with Perceptor getting several bits of analytical dialogue. But from page 23, Silverbolt suddenly replaces Perceptor, and has an important role in the climax of the Speedia race.
- In several parts of the book, Optimus claims that he ejected the Allspark to stop Megatron from corrupting it with Dark Energon. However, in Exodus, Optimus ejects the Allspark long before Megatron gets his hands on Dark Energon and uses it to infect the Core.
- Similarly, page 25 identifies the second Velocitron landing team as Sideswipe, Hound, Ironhide and Prowl, but from page 29, Ironhide is replaced with Ratchet.
- At the end of chapter five, Optimus Prime and Clocker drive away and leave the monolith behind, but then at the start of chapter seven, they're suddenly back in front of it again as if they'd never left.
- Page 209 makes the claim that Makeshift cannot even change his facial expressions while in the statis field, but the rest of his interrogation scene repeatedly describe him doing just that.
- On page 218, Optimus decides to have Silverbolt provide the transport for the mission to the space bridge, rather than using the ship they had previously salvaged. This notion is carried through, with the Aerialbot described as carrying Prime and Bumblebee into orbit (p. 234), and they subsequently move around the space graveyard without a ship. However, when the group departs from Solus Prime's tomb, they go "back to the ship", and are said to board the salvaged spacecraft with Sideswipe at the helm (p. 267). This doesn't last long, as when they enter the other space bridge and return to Junkion (p. 271), it is back to just the "four bots" (Chaindrive has joined them), with no ship.
- On page 276, Sideswipe joins the conversation, despite Ratchet and Jazz being the only Autobots described as joining up with Optimus' party.
- It's never explained how exactly Optimus manages to travel to Velocitron's south pole and back in such a short time.
- The final few chapters have a lot of trouble with the names of swords. While the rest of the book talks about the fragments of the Star Saber, once Nexus Prime is formed, the sword he produces and gives to Optimus Prime is called the "Cyber Caliber". Logically, one might immediately assume that this is a different sword and that the Star Saber is still out there somewhere else, but when the fight is over, the sword is broken up into fragments like the Star Saber and integrated into each of Nexus's components, and in the epilogue, Alpha Trion again refers to Nexus Prime as possessor of the Star Saber. The Transformers: Prime episode "Legacy" further confounds the issue by having the real Star Saber show up on Earth, apparently launched from Cybertron by Alpha Trion, near the end of the war.
- Similarly, Nexus Prime's personal blade is at first called the "Omni Saber" in one instance, and then in the subsequent two instances of it being named, is called the "Chaos Edge". Alex has confirmed via Twitter that the Saber and Caliber are separate swords not an error (so he claims at least), whether the same is true of the other two and Nexus is toting four unrelated swords around inside him, who can say...
- The entire book revisits the idea of lost Cybertronian colony worlds; something which was initially explored in the Transformers: Cybertron franchise.
- Velocitron and many of its inhabitants are re-imagined versions of Cybertron Velocitronians.
- Junkion first appeared in the Generation 1 continuity family. Accordingly, Wreck-Gar and Detritus are similarly updated versions of classic Generation 1 characters.
- Wreck-Gar's cheerful proclamation of "that's what I'm good for, garbage!" recalls a different Wreck-Gar and his perceived lot in life.
- The universal greeting is used several times in the book.
- Alpha Trion mentions that the Star Saber may be made up of three smaller robots; in its Armada incarnation, the Star Saber was just that.