The Mark on the Door

Frank and Joe Hardy, aboard their motorboat Sleuth, pursue a mysterious thief in Barmet Bay. When the stolen boat drifts into the fog, the brothers, joined by Chet Morton, embark on a thrilling chase. Their quest leads them to the untamed deserts and mountains of Baja California, where danger and intrigue await. Can they unravel the mystery and catch the elusive stranger before it's too late? Adventure and suspense unfold as they navigate unknown territories.