Green Hill Zone's golden sunshine is shattered by the whir of metal wings-Metal Sonic, leading a legion of Badniks and airships, cuts through the sky toward Angel Island. For Sonic the Hedgehog and his loyal friend Tails, this is no random attack; it's the start of a quest that will drag them into a realm of ancient magic and interlocking evils. When the Master Emerald, the source of Angel Island's flight, is stolen by the mechanical menace, Knuckles the Echidna joins the chase, driven by duty to reclaim his people's most sacred treasure. Not far behind is Amy Rose, her courage unshaken as she races to stand with the hero she admires.