The family ride a jet belonging to Grandpa Max’s old Friend, Donovan Grand Smith, who owns an underwater resort. At the entrance, they receive a warm welcome from Donovan himself, though they also meet with his grandson, Edwin, who doesn’t seem to be excited about their guests. Later, when Edwin, Ben, and Gwen enter the Undersea Manta Ray, a giant submarine, they encounter strange aliens that threaten to destroy the whole resort. While the kids find a way to cooperate with each other to find the source. The aliens want to retrieve as it turns out that it was a piece of their technology, Donovan himself learns a few lessons in how to bond better with his grandson.