S03 E15 - Mission of Gravity

The Turtles are overjoyed to encounter an old friend who they thought was dead, and they all set out to lower the floating city of Beijing back to the Earth's surface. Going against her adopted father's wishes, Karai turns to the Turtles' for assistance-not wanting to have millions of innocent people perish-while Baxter Stockman, whose technological skills are at risk of being usurped, tries to get rid of Dr. Chaplin.

Original air date: February 5, 2005