The year is 1913. The steamship SS Atlantica is two days out of port on its journey across the Atlantic Ocean. The unsuspecting passengers fully anticipated an uneventful journey to Boston, Massachusetts, with nothing in particular to look forward to. However, strange nightmares plague the minds of those aboard the ship every night; rumors circulate of dark shapes following just beneath the waves behind the ship; and tensions rise when a body is discovered in the ship's chapel, signs of a strange ritual surrounding the corpse. This journey started like any other, but now it seems the Atlantic will never reach its destination.

Immerse yourself among the passengers and crew of the SS Atlantica in this game of hidden loyalties, intrigue and paranoia for three to six players. Some players are people fighting for the ship's survival, while others are traitors sent aboard by mysterious beings to ensure it never reaches port! Since player loyalty is hidden, determining who is friend and who is enemy is crucial to winning an exciting game of Unfathomable.