When GUTS-Select investigate mysterious disappearances, they learn it is work of an evil alien who intends to invade the Earth, called Professor Gibellus. However, just in time, a mysterious woman appears to help GUTS-Select.

Set two years after the events of Ultraman Trigger, an ultra-ancient threat re-emerges, leading to the return of Ultraman Trigger and Ultraman Zett to save the day, but all is not as it seems.