World War II, 1944. Somewhere in the jungle, Jacob Thomas peers out from behind bamboo bars at his keepers. His 16 months of captivity have been spent digging a large tunnel into the side of a mountain. The only thing keeping him alive is the promise he made to his wife that he would come home to her. Almost six decades later in upstate New York, Connor Mason receives a coded message from his missing father's estranged partner, exposing a secret life and a treasure half a world away. For him the adventure is about to begin.