Transformers: Constructicon Mayhem is the fifth movie in the second Transformers Trilogy. Starring Shia LeBouf as Sam Witwicky, Megan Fox as Mikaela Banes, Josh Duhamel as William Lennox, John Turturro as Seymour Simmons, and Peter Cullen as Optimus Prime. Tyrese Gibson returns as Robert Epps. Kevin Dunn and Julie White also return to their roles as Mr. and Mrs. Witwicky. Also, Lester Speight returns as "Hardcore" Eddie, and Glenn Morshower returns as General Morshower.
The Transformers have been living in peace for a week after the Decepticons defeat. The Autobots are Optimus, Bumblebee, Primon(After they grabbed some powder from Barricade), Bluestreak, Ironhide, Wheelie, Prowl, Ratchet, Inferno, Arcee, and Wheeljack. The Transformers have a new threat, however, called the Constructicons. The Leader, Scrapper, has gathered up every Constructicon((Himself, Hook, Bonecrusher, Scavenger, Long Haul, Mixmaster,) (Heavy Load, Hightower, Grimlock, Wedge) (Steamhammer, Duststorm, Sledge, Wideload)). They all combine into the 3 Constructicons, Devastator, Landfill, Constructicon Maximus, and find the fourth, Demolisher, to destroy the Autobots. They bring back four Decepticons to help, Starscream, Galvatron, Skywarp, and Shockwave. They all attack New York, and bring the Autobots to them. Sam and Mikaela have to stay behind, having no weapons.The Autobots arrive, and get mauled. The only surviving Autobots are Primon, Bumblebee, Wheeljack, Inferno, and Ironhide. The remaining Autobots bring the bodies of the fallen allies, including Wheelie. Mikaela and Sam do their best to bring back the dead, but they need Cybertronian tech. Sam and Mikaela, with Wheeljack, Bumblebee, and Wheelie, head back to the Spacecraft from Behind the Stars. They take the Life Support used by Arcee. They split it to use on each dead Autobot. They talk to NEST, which Lennox is now leading, and Hardcore Eddie has returned to. They, along with NEST, and Sam and Mikaela, plan to head back to NY. First, they head to London, rumored to be where the Constructicon landing site is. They find the site, and they choose two groups of four that can transform into two different Constructicons. They choose Optimus, Ironhide, Primon, and Bumblebee for the first, and Ratchet, Inferno, Prowl, and Wheeljack for the second. They head back to NY. The new Constructicons, Autobot Constructicon(Optimus, Ironhide, Bumblebee, and Primon) and Pyronite(Inferno, Ratchet, Prowl, and Wheeljack) start fighting Devastator and Landfill. The Autobots dominate, and the four Decepticons combine to for the Decepticon Constructicon. Autobot Constructicon (AC) fights Decepticon Constructicon (DeC(Not DC for copyright reasons)) while Pyronite fights Constructicon Maximus (CM). AC and DeC are fighting, and it is a neutral fight. Pyronite is losing badly to CM, but AC interrupts and decapitates CM. AC and Pyronite comebine to make Constructicon Maximus 2.0(CM2.0). CM2.0 and DeC still fight evenly, and Sam intervenes with a crane, and throws the wrecking ball into DeC, severely injuring him. Mikaela grabs a the most recent bomb design, 2 big steps down from a nuke. She tosses it off a NY building and blows off half of DeC's face. NEST hops in and starts shooting Bazookas and the Bomb Mikaela used at DeC, blowiing off his arms and a leg. CM2.0 uses Optimus' blade to decapitate the rest of DeC's head. Meanwhile, Bluestreak, Wheelie, and Arcee defeat the rest of the Mini Decepticon Army. After DeC's head is decapitated, just like every other Constructicon, they split back into four. CM2.0 splits back into AC and Pyronite, and finally split back into the eight Autobots. Sam, Mikaela, NEST, and the 11 Autobots reflect their past, ad how Megatron somehow keeps coming back. They decide it was never going to end, and they should just fight whenever they can.