Following a report of strange aircraft heading for the Floating Island, Sonic and Tails go after them, only to discover a Drakon invasion force. Reasoning that they're after the Chaos Emeralds, Sonic orders Tails to land the bi-plane somewhere, and leaps right into battle. While Sonic grapples with the Sentinels, the leading Prosecutor orders half of the Sentinels to follow him. They quickly find a metal ring in the ground a short distance away, just part of a hatch leading to the island's secret tunnels. Suddenly the Sentinel entering the tunnel is blasted away as a Guardian Robot joins the battle. The Prosecutor leads two Sentinels into the tunnel while the others stay to fight the robot, and they soon break through to the Emerald Chamber. The Prosecutor prepares to retrieve the Emeralds