Following their last battle, Dr. Eggman's been mysteriously absent from Sonic's life. What shocking secret will Sonic discover when he learns the bad doctor's whereabouts? Plus, Sonic isn't the only one looking for Eggman--so's his old frenemy Shadow the Hedgehog! There are twists and turns in the course of this high-speed, action-packed mystery-adventure! But with a little help from his friends--including a new ally--Sonic's fast enough to overcome...

"When Neo Metal Sonic--an evil robot with Sonic's speed, Dr. Eggman's intellect, and an unbreakable mechanical body--conquers the island to grow his power even more, Sonic and his friends must team-up and take the fight to him. But even with the full power of the Resistance behind him, will Sonic be able to take down Neo Metal Sonic once and for all?"--Provided by publisher.