The last show that I know of in this series, and I had a time in finding this one.
Previously Buck and Barney had both taken their own mechanical moles underground, unknown to each other. Their exploration had brought them head to head, and almost led to them blasting each other. Now that they realize they are safe, Barney is upset to find his little pal gone. The worry is unfounded since Pete made his way through a different tunnel to find Wilma Dearing in her mechanical mole.
With everybody safe, and accounted for, Buck and Barney plan to finish their trip, and head back to the surface. Back on the surface with a successful mission complete, our heros get ready to report to the president. Word comes that they may be heading out on another adventure. One that’s more dangerous than any they’ve had before.