Thomas and Twilight Sparkle's Adventures of Rambo III is the third upcoming Thomas/MLP/Rambo crossover made by Stuigntion. And the sequel to Thomas and Twilight Sparkle's Adventures of Rambo: First Blood Part II.
Colonel Sam Trautman visits his old friend and ally John Rambo in Thailand. He explains that he is putting together a mercenary team for a CIA-sponsored mission to supply anti-Soviet fighters in Afghanistan. Despite being shown photos of civilians suffering at the hands of the Soviet military, Rambo refuses to join, as he is tired of fighting. Trautman proceeds anyway and is ambushed by enemy forces near the border, resulting in all of his men being killed. Trautman is captured and sent to a large mountain base to be interrogated by Soviet Colonel Zaysen and his henchman Sergeant Kourov.
Embassy official Robert Griggs informs Rambo of Trautman's capture but refuses to approve a rescue mission for fear of drawing the United States into the war. Aware that Trautman will die otherwise, Rambo gets permission to undertake a solo rescue on the condition that he will be disavowed in the event of capture or death. Rambo immediately flies to Peshawar, Pakistan, where he intends to convince arms dealer Mousa Ghani to bring him to Khost, the town closest to the Soviet base where Trautman is held captive.
The Mujahideen in the village, led by chieftain Masoud, hesitate to help Rambo free Trautman. Meanwhile, a Soviet informant in Ghani's employ informs the Russians, who send two attack helicopters to destroy the village. Though Rambo manages to destroy one of them with a turret, the rebels refuse to aid him any further. Aided only by Mousa and a young boy named Hamid, Rambo attacks the base and inflicts significant damage before being forced to retreat. Hamid, as well as Rambo, are wounded during the battle and Rambo sends him and Mousa away before resuming his infiltration.
Skillfully evading base security, Rambo reaches Trautman just as he is about to be tortured with a flamethrower. He and Trautman rescue several other prisoners and hijack a Hind helicopter to escape the base. The helicopter is damaged during takeoff and quickly crashes, forcing the escapees to flee across the sand on foot. An attack chopper pursues Rambo and Trautman to a nearby cave, where Rambo destroys it with an explosive arrow. A furious Zaysen sends commandos under Kourov to kill them, but they are quickly routed and killed. An injured Kourov attacks Rambo with his bare hands, but is overcome and killed.
As Rambo and Trautman make their way to the Pakistani border, Zaysen and his forces (along with Tirek, Starlight, and Bellwether) surround them. But before the team are overwhelmed, Masoud's Mujahideen forces (aswell as a surprise attack from the Wonderbolts and Skipper) attack the Soviets in a surprise cavalry charge. Meanwhile, Judy engages Bellwether into a duel and is joined by Buttercream. But the sheep manages to give them slip and escape the battle. Tirek then starts firing fireballs at the team, in despite to kill them. But then Nick (with help from Percy) hops into the Trolley Fighters' anti-artillery turret, and with Percy pushing, he draws fire at Tirek. Then Starlight also engages Twilight in a duel, but she overwhelms Twilight, and almost kills her when Blythe jumps into the duel and as the 2 come into a blade lock, Blythe quickly kicks Starlight in the shin, and as Starlight winces in pain, Blythe uses the distraction to destroy Starlight's Lightsaber, and slightly slashes her horn, making her unable to conjure magic. Then Percy manages to get to full speed and with Nick continuing to draw fire, Tirek charges to the 2 still firing fireballs. Despite being wounded, Rambo takes control of a tank and uses it to shoot down Zaysen's chopper. The two collide but only Rambo survives. As Percy and the turret are inches away from Tirek, Nick fires the turret which blasts Tirek square in the chest, causing a huge fireball and smoke screen, then when they clear away, Tirek is laying on the ground, dead. Then in a great rage, Starlight shoots Twilight, (seemingly killing her). And before she can do the same for Spike, Judy fires first, and Starlight collapses to the ground, dead. While, Bellwether leaves, claiming she'll get them next time. At the end of the battle, Rambo and Trautman say goodbye to the Mujahideen and leave Afghanistan.
- Princess Celestia, Princess Luna, Zecora, Stephen, Button Mash, Babs Seed, Maud Pie, Figge, Dusty Crophopper, Ishani, Steamy, Puffy, Evan, Timber, Splinter, and Chomper, Big Grizz, Shai-Shay, Rodger, Willy, Mako, Sharky, J.J., Falcon, Hugs, T.C., Sherin, 1206, Buzz, Socky, Skunky, Whiffle, The Miner Trains, The Planet Trains, General Dedrich, The Trolley Fighters, Rattlesnake Jake, Dudley Puppy, Kitty Katswell, Jenny Wakeman, Mordecai, Rigby, Skips, Benson, Pops, Muscle Man, Hi Five Ghost, Margaret, Eileen, Princess Anna, Elsa the Snow Queen, Princess Merida, Vanellope von Schweetz, Ed, Edd, n Eddy, Blythe Baxter, Zoe Trent, Pepper Clark, Penny Ling, Vinnie Terrio, Sunil Nevla, Minka Mark, Russell Ferguson, Mitzi, Buttercream Sunday, Sugar Sprinkles, SpongeBob SquarePants, Patrick Star, Squidward Tentacles, Eugene Krabs, Sandy Cheeks, Judy Hopps, and Nick Wilde guest star in this film.
- Dawn Bellwether, Starlight Glimmer, and Tirek will work for Colonel Zaysen.
- Events from Little Bear's Adventures of My Little Pony: Friendship is Magic - Twilight's Kingdom, Little Bear's Adventures of My Little Pony: Friendship is Magic - The Cutie Map, Thomas and Twilight Sparkle's Adventures of Batman v Superman: Dawn of Justice, and Brian and the Eeveelution Family's Adventures of Lord of the Rings Trilogy are mentioned in this film
- The storyline concludes in Thomas and Twilight Sparkle's Adventures of Rambo.