I have an idea...........
3 years has passed since the events of the 1st movie.
While on a routine mission searching for fuel source on earth, Ironhide begins to recieve a faint communication. Its cybertronian, origin earth, central Africa. Ironhide immediatly reports via there means of cybertronian radio to Optimus Prime. Prime orders Ironhide, currently in Iran, to investigate the signal and to give him the exact co-ordinance so he can join him. Several hours has passed and Prime recieves the possition of Ironhide. Prime then sets out for Africa.
Prime eventually arrives at Ironhides location to see his old friend busy scanning the base of a large mountain. Ironhide reports "Chief, its definatly of cybertronian origin, its on a loop and is encrypted, I can not break the code. If only Jazz were still around". Prime recognises the signal and decodes it. A voice announces in cybertronian "THIS IS ARK, REQUESTING ASSISSTANCE. THIS IS ARK, REQUESTING ASSISSTANCE. THIS IS ARK......" Prime turns off the signal. Ironhide shocked turns to Prime. "Is this even possible, the Ark has been missing since The Great War". "Correct." Prime replies. "It was I that gave the order to launch, it was presumed destroyed after Megatron discovered its mission, to recover the All Spark." Ironhide ponders. "It makes sense that the Ark is here, if they found the whereabouts of the all spark here on earth then thats how Megatron found it here". Optimus begins to scan for the Ark, it is pin-pointed at around 450 metres below the base of the mountain. "Who was part of the crew?" Ironhide asks. "Fleet Commander Prowl, accompanied with Cliffjumper and Wheeljack." Prime answers as he finishes his scans. "Could they still be functional? After all this time concealed below the earths surface." Ironhides question provides incentive for what Prime than answers, "There is only one means to find out, but we will need help, time to see our human friends." With that, Optimus Prime begins to make plans.
I might continue this if I get inspired, I have an idea for bringing Shockwave into the story with Starscream making it back to Cybertron to regroup amongst other plot ideas.