Escaping death in the Arbor Cafe earthquake, Cleo and Hope examine the book. In it Cleo finds a prescription which Dr. Owen left there. Olga and Morton see this and think she has found the secret of the submarine. They follow Cleo and Hope. En route to San Francisco, Olga and Morton lose track of Cleo and Hope, Mahlin and Satsuma are close on their heels. Olga and Morton meet Smith, an aviator who taught Morton how to fly an aeroplane. While waiting for Hope to recover from a slight injury received in the earthquake, Cleo and Hope attend an aviation meet. They see Smith make a flight with a fellow passenger, the latter descending in a parachute. Cleo and Hook are seen by Olga and Morton. On the way back from the aviation meet, Cleo is kidnapped by Olga and Morton when Hook strolls away to buy a newspaper. They demand that she divulge the secret of the submarine. She tells them paper she found in the book was a prescription. They refuse to believe her. Hope and Hook make a desperate but ineffectual search for Cleo. That night Morton steals Smith's aeroplane and starts across the mountains with Cleo to take her to his hunting cabin. When over the mountain, Cleo suddenly grabs the parachute and descends to earth. She is quickly followed by Morton in the aeroplane. They have landed on a mountain where Dick Patten, a recluse, has a cabin. Morton finds a letter which tells him Patten will be away for two weeks. The only means of access to the mountain is in a basket over a cable that crosses a chasm. Morton tells Cleo she must remain here until she will consent to reveal the secret of the submarine. He tells her he will return the following day. In the morning Cleo makes a small parachute of her handkerchief and sends a note flying down from the mountain in hopes someone will find it. It is found by two boys, who turn it over to their mother. The mother goes to the hotel to take the note to Lieut. Hope. Mahlin and Satsuma get the note from the women and are reading it when Hope comes in. He grabs the note and they flee. Hope and Hook start for the cabin on the mountain. Mahlin and Satsuma are also en route. Aviator Smith has notified the police of the loss of his machine. Morton with Olga in the aeroplane starts for the mountain gain to demand that Cleo divulge the secret of the submarine. Aviator Smith and a squad of motorcycle police trail Morton. Hope arrives at one side of the chasm and sees Cleo on the opposite side of the cable. Hook is toiling up the mountain side some distance below. Hope starts to cross the cable hand over hand. When he reaches the center, Mahlin and Satsuma run up. Mahlin grabs an axe and cuts the cable as Cleo looks on in helpless horror. - Moving Picture World, July 22, 1916
See Episode One for cast listing.