The Dark Past (Teresdon) - S1.E4

A pair of seismologists working in a remote cavern have detected unusual underground activity. Theresa Beck & Kenichi Kai are sent to investigate and Kai disappears when another tremor rocks the cavern. While Beck tries to console herself for losing Kai, the rest of the WINR team has determined that the seismic activity is being caused by a strange object moving underground toward the city.