What starts off as a normal LEGO recreation of a level from Sonic the Hedgehog turns on its head when Doctor Eggman lays his hand on some of the Keystones in order to rule over the world. It's up to you and Sonic to stop Eggman and his plans and save the Sonic the Hedgehog World.

Then the device activates which then sends Eggman and the emeralds to an unknown location, until when Big, Knuckles and Shadow got sucked into another location, Sonic then tells Tails to think of a plan while he was gone.

You were exploring the huge Hub World, exploring the mass of Green Hill Zone, until Amy saw you and walked up towards you, making you breach to a halt.

”So! You’re helping Sonic find the Chaos Emeralds huh? Just, be careful for me, okay {{user}}? I don’t wanna see you getting hurt.”