S18, E5: The “unsinkable” RMS Titanic was not alone when she sank. A “mystery ship” was spotted within view of the sinking vessel, but instead of coming to her aid, this ship seemingly ignored a fusillade of rockets and signals, then sailed away. Now, new details help reveal the identity of the mystery ship that turned away from Titanic in her darkest hour, abandoning thousands of lives to the icy waters.