Crap story just like all the other games in the 'Souls' franchise

The main sell of these games are the difficulty and the sense of self-gratification defeating it. If anyone's expecting that this time there is a better story driving it to justify the headache of beating it and planning on getting the game, forget it. Nothing's changed at that department.

Here's the plot summary from Wiki, nothing to shout about.
The game takes place in a decrepit Gothic city called Yharnam, which is known for its medical advances using blood as their primary tool. Over the years, many travelers journey to the city seeking the remedy to cure their afflictions; the player takes the journeys to Yharnam seeking a powerful blood known as Paleblood for reasons unknown. Upon arriving in the city, however, it is discovered that the city is plagued with an endemic illness that has transformed most of its citizens into bestial creatures. The player must navigate the streets of Yharnam and overcome its violently deranged inhabitants and horrifying monsters in order to survive.

Shortly after their arrival in Yharnam, the player encounters a spectral realm called the Hunter's Dream, which acts as both a sanctuary and workshop. The player encounters two entities: Gehrman, an elderly, wheelchair-bound man who provides advice to Hunters like the player, and the Doll, a living life-size doll that assists the player in leveling up. Gehrman informs the player that in order to obtain the blood they seek, they must hunt down the various monsters plaguing Yharnam. As the player delves deeper into the city, they begin to learn its dark secrets, as well as the origin of the plague that's destroying it. Long ago, the residents of Yharnam began worshiping ancient, eldritch beings called Great Ones. The Great Ones provided the miracle remedies Yharnam was famous for, which are also the source of the plague. The plague was spread in Yharnam by the Great Ones in order to foster the growth of an infant Great One called the Moon Presence.

Eventually, the player succeeds in obtaining the remedy. Gehrman offers to free the player from the Nightmare and return them to the Waking World. At this point, three different endings are possible depending on the player's actions.

Choosing to accept Gehrman's offer unlocks the Yharnam Sunrise ending. Gehrman uses his scythe to behead the player, who then awakens in the real Yharnam as the sun rises. In the Hunter's Dream, the Doll bids the player farewell.

Choosing to refuse Gehrman's offer unlocks the Honoring Wishes ending. Angered, Gehrman initiates a battle with the player. After Gehrman is defeated, the Moon Presence arrives and embraces the player, binding him to the dream. Some time later, the Doll is seen pushing the player, now sitting in Gehrman's wheelchair, back to the mansion in the Hunter's Dream. The Doll remarks that a new Hunt will begin, signifying that the player has taken Gehrman's place in guiding other Hunters.

If the player consumes three pieces of an Umbilical Cord and refuses Gehrman's offer, the Childhood's Beginning ending is unlocked. After Gehrman is defeated, the Moon Presence arrives to devour the player, but the player resists. The Moon Presence then initiates a battle against the player. Upon defeating the Moon Presence, the player is transformed into an infant Great One, destined to replace the Moon Presence.