While pursuing the fugitives, Urko is caught in an earthquake and trapped in an underground subway station... with Pete. To free them both, Alan and Galen must make a deal with Urko's lieutenant, Zako.

The trio find a long-buried human science institute, but the projector revealing the vault of hidden knowledge is out of power. While Pete and Galen collect parts to make a battery, Urko and Zaius capture Alan and try to obtain the institute's location from him.