Соник Андерграунд

What is supposed to be a vacation for Sonic, Manic and Sonia turns into a battle to save Mobius when Robotnik attacks with his newest weapon - the Flying Fortress. Sonic investigates the ship thinking the weapon can be destroyed by removing its reactor, however his efforts fail and he goes to Knuckles for help, because he believes the weapon is powered by the Chaos Emerald.