Ep 1. Beneath These Streets

In the third season premiere of Teenage Mutant Ninja Turtles (1987), titled "Beneath These Streets," the turtles find themselves investigating strange earthquakes that are occurring all over New York City. They soon discover that these earthquakes are being caused by an underground civilization of mole people, who are upset about their homes being destroyed by the construction of the city's subway system.

The turtles decide to help the mole people, but they soon find themselves in a dangerous situation when they are captured by the mole people's queen. The queen, who is suspicious of outsiders, believes that the turtles are spies who have been sent by the surface world to destroy her people's home.

As the turtles try to convince the queen that they are on her side, they discover that there is a much greater threat to the mole people's home: an evil scientist named Professor Willard W. Willard, who has been using his giant drill to destabilize the underground tunnels. Willard wants to use the tunnels to transport stolen treasure from a museum to his secret laboratory.

The turtles and the mole people team up to stop Willard and his henchmen, but they soon discover that the drill is too powerful for them to stop on their own. With the help of their human friend April O'Neil, the turtles manage to contact the surface world and alert the authorities to the danger.

In the end, the turtles and the mole people are able to stop Willard and his plan, and the mole people's home is saved. The turtles leave the underground world, proud of what they accomplished, and ready for whatever challenges they'll face in the future.