After a search and rescue mission to save a stranded trading vessel in the North Atlantic, men onboard the HMS Heroic start dying of unknown causes. The HMS Heroic struggles to find their way to shore with limited sailors, dated navigation, and a mysterious ailment killing off more and more crew by the day. Will the Royal Navy of the HMS Heroic survive the unrelenting conditions of the North Atlantic, or will they all perish from the many dangers they face?