Abstergo Industries has opened an entertainment subsidiary in Montreal, Quebec, using advanced technology to relive fragments from people's past lives. The unnamed protagonist is hired by the company to connect with Edward Kenway, a Welsh privateer living in the eighteenth century. Through a series of events, Edward assumes the identity of a rogue Assassin reporting to Laureano Torres, the Governor of Cuba and Grand Master of the Templars.
The game's world is larger than in any previous games, and is available for exploration in a seamless fashion without transitions or loading between ship navigation, swimming, and exploring the land. Much of the Caribbean Sea can be physically explored, including three full-fledged cities (Havana, Kingston, and Nassau) as well as smaller settlements and uninhabited islands. The protagonist can hunt animals, fish, and uncover treasure maps. Early in the game Edward gains access to the Jackdaw, a ship that can be outfitted, upgraded, and used in naval battles.