Castaways - S1.E13

Troy is headed to the strife torn island of Mai Sai with a cargo of serum to fight a cholera epidemic. Troy and crew pick up three men stranded on a tiny atoll, who claim to be survivors of a shipwreck, but they're really gunrunners from a ship called the Punjab Trader, whose captain was murdered. The trio, led by the second mate, take over the Tiki, threatening to kill the nun who is transporting the serum, and go after the Punjab Trader.