Challenge of the Transformers is an American computer-animated television series based on the Transformers toy franchise by Hasbro that may air on either Cartoon Network or Adult Swim.
It focuses on a small team of Autobots, which consists of Optimus Prime, Ratchet, Arcee, Bumblebee and Ironhide. Throughout their battles, the Autobots are aided by three human children and with their help attempt to protect the Earth from the villainous Decepticons and their leader Megatron.
It features toys from the Studio Series toyline.
Challenge of the Transformers is set in the "Siege" continuity, taking place after the web series, Transformers - War for Cybertron: Siege.
In the series’ backstory, millions of years ago on the planet Cybertron, there lived a race of human-like organic beings referred to as “Cybertronians.” Civil war erupted on the planet when the power-hungry terrorist group known as the Decepticons arose, led by a madman named "Unicron", who waged war against the peaceful Autobots.
However, a group of geniuses who became known as the “Dynasty of Primes” saved their people, taking their experiments to replace parts of their own bodies with mechanical substitutes to the ultimate extent and transferring the brains of the Cybertronians into large robots known as "Transformers".
The Transformers possessed an additional ability; after being run through the device named the Oracle, the Transformers’ bodies were able to transform into other vehicles. With their work done, the Dynasty of Primes intended to retreat to a pre-prepared workshop elsewhere in the galaxy, but Unicron stole their ship and escaped in their stead. The Dynasty of Primes placed themselves into suspended animation beneath the surface of Cybertron, while above, the war continued to rage between the Autobots and the Decepticons, now all encased in Cybertronian shells.
Time passes to present day, and although tyrannical Megatron, Unicron's successor, was captured and convicted of terrorism and government corruption thus sentenced to Graviton Prison, a maximum-security holding facility located in the mouth of the Black Hole, his dedicated general, Starscream, steals the Astro Beam, a device which opens and portal to the Graviton Prison, and flees Cybertron on his master's mothership, the Nemesis, to find a safe place to free Megatron without Autobot interference. An Autobot security squadron (consisting of Optimus Prime, Bumblebee, Ratchet, Ironhide, Arcee, Chromia, and Elita-1) try to give chase, but the Nemesis knocks their patrol ship, the Ark, off course, causing it to crash into Earth where they are discovered, hospitalized, and reformatted into their new alternate modes by N.E.S.T. (short for the "Nonbiological Extraterrestrial Specialist Team"), a special strike force founded by the United States Army.
The series opens with the Biker Triplets (an all-female fireteam led by Elita-1) attempting to recover Energon and return it to base, only to end up being confronted by a security squad of Shadow Raiders, and then Starscream, who claims that for stealing his most precious thing in the world, i.e. Energon, the Biker Triplets must die. Although Arcee survived, but her older sisters, Elita-1 and Chromia were unfortunately executed by recycling.
Devastated by her sisters' death, Arcee now seeks vengeance on the Decepticons for their act of murder. Meanwhile, Optimus Prime recruited three high school students, Spike Witwicky, Chip Chase, and Carly Spencer into becoming the new generation soldiers of N.E.S.T.
Since the series premiere episode ended with Megatron being freed from Graviton Prison by Starscream (an announcement made by N.E.S.T CEO and founder, General Glenn Morshower), the Decepticon tyrant himself now plans a series of vengeance against the Autobots, starting with the use of Elita-1's and Chromia's corpses as test subjects for his Dark Energon experiments, which he intends to use to create an undead army from Cybertron’s fallen warriors.
The Autobots later found the true Dynasty of Primes, who were instrumental in frustrating the alliance between Megatron's Decepticons and Unicron. Unicron later escaped the custody of the Decepticons, and plagued both factions, bent on destroying the entire universe. As a consequence, the Autobots and Decepticons form an uneasy alliance to destroy Unicron for good.
The series ends with the lasting truce between the Autobots and Decepticons before both factions return to Cybertron to finally rebuild their home.