Part one of a two-part story. After the Freedom Fighter Special makes a crash landing, Sonic and Tails perform a little reconnaissance and find themselves up against the menace of Metal Sonic.
Against the Haunted Past
The history of Monkey Khan.
Heart of the Hedgehog - Part One: Evil's Return
The story opens with Sonic and Tails on a recon mission, which Sonic turns into a training run for Tails. After a near-crash landing, Tails feels as though he's not able enough to be as skilled as Sonic. Sonic reassures him that he'll eventually succeed and the two break for lunch. Tails flies off to gather firewood for their campfire, but fails to return after an hour has passed. Fearing that he may have discouraged him, Sonic heads out to search for Tails, only to be ambushed by a familiar-looking robot... Metal Sonic.
Metal Sonic reveals that he has managed to rebuild himself from his past defeats and is ready to resume his task of destroying Sonic (though he's also got plans for Knuckles afterwards). Sonic is quickly overpowered and incapacitated by Metal Sonic's new-and-improved design, and the hedgehog realizes that Metal Sonic still has a shard of a Power Gem on him (which he had originally used during the Chaotix special), which also explains his newly-arrogant personality despite still operating on his programming. Metal Sonic gloatingly tells Sonic that he has captured Tails and has taken him to Mt. Mobius, which is set to erupt very soon, and challenges Sonic to rescue him before it erupts.
As expected, Sonic accepts the challenge and runs all the way through the forest. His pace, however, is eventually interrupted when Metal Sonic suddenly pops out and sucker-punches Sonic in the face. With Sonic unconscious, Metal Sonic dashes back to Tails and demoralizes him with the news, though the fox remains defiant.
Despite the cover giving Metal Sonic a Sonic-based appearance, his eyes are black (unlike the cover).