The world's largest ocean has a way of keeping its secrets.

Across the endless expanse of the North Pacific, ships have vanished... submarines have disappeared... and airplanes have simply slipped into history without a trace.

On July 21, 1951, one routine flight joined that haunting list. A Canadian Pacific Air Lines Douglas DC-4 departed Vancouver for Tokyo carrying thirty-seven souls, many of them United Nations personnel on an important mission. The weather was calm. The aircraft was experienced. Nothing appeared out of the ordinary.

Then, somewhere between civilization and the endless horizon... the radio fell silent.

More than seventy years later, the Pacific still refuses to reveal what happened aboard Canadian Pacific Air Lines Flight 3505. Tonight, we'll retrace t ...