Tonton Streaming Sonic Underground (1999) S1E23 - Hedgehog in the Iron Mask

The Hedgehogs latest quest to find their mother takes them to the prison tower where they encounter a masked stranger who insists he is family. This stranger is actually being used as bait for another attempt by Robotnik to capture them. The stranger creates a rift between the siblings, which leaves the Underground disbanded, vulnerable and ultimately trapped.