Sonic, Tails, Knuckles and Shadow are back for another breakneck adventure, and this time the team gains a new member: Amy Rose, a spirited, fiercely determined young hedgehog with a mighty hammer and an unshakeable devotion to Sonic. With the scheming Dr Robotnik once again at the centre of the chaos, the powerful Chaos Emeralds in play and a sinister robotic double of Sonic on the loose, the blue blur and his friends, along with their human allies Tom and Maddie Wachowski, must work together to save the day.