"No Hedgehog is an Island" is the twenty-seventh episode of the Sonic Underground television series and the second of three episodes in the Chaos Emerald Crisis mini-series. It first aired on 7 April 1999 in France and on 5 October 1999 in the United States. It was included in Volume 2 and Secrets of the Chaos Emerald.
The song performed in this episode is "Learn to Overcome".
Sleet and Dingo escape the Flying Fortress with the Chaos Emerald. In a fight over who will control the Emerald's power, Sleet and Dingo drop and break the Emerald in two. Instantly, a rash of earthquakes and other natural disasters are sparked by the emerald's energy. Knuckles and the Hedgehogs turn to a relative of Knuckles for answers of how to stop Mobius from being slowly devoured by the emerald's force and find that the only solution to end the obliteration of Mobius is to make a deal with their arch rival Robotnik.