TMNT Episode 15 - Notes from the Underground, Part 3 Episode Title:Notes from the Underground, Part 3.Episode Description:The source of the mysterious crystals found in the lair appears to be an ancient subterranean city. This site is also the location where Donatello and the Turtles' monster allies disappear. The city is inhabited by the sole survivor of an ancient race. Although he claims wanting to return the creatures to their original form, his true intentions remain unknown. The Entity to attack the Turtles, but Michelangelo uses a light orb to encase the Entity in ice crystal. The Turtles free Quarry to find that he, is actually a she! All of the other mutants are also returned to normal when freed. However, they find out as they try to leave the city, are only cured by the power of the crystals and have to stay in the city to keep their human form. Donatello vows to find a solution that will let them return above ground. On the way home, the Turtles they find out that the Foot are searching for them and the Lair is not safe, so they go into hiding at April's place.