In “Blood and Wine,” the latest (and final) expansion for CD Prokjekt RED’s The Witcher 3: Wild Hunt, a serial killer is on the loose. The people of Toussaint—a sort of fantasy Southern France—are terrified by the bodies of prominent knights found mutilated each day. In order to discover who (or what) is responsible for the murders, Geralt, The Witcher’s monster-hunting protagonist, finds himself tracking a rare ingredient: the saliva of an undead creature.

In most other role-playing games, the player would likely need to kill a quota of monsters to get this item. In “Blood and Wine” Geralt has to investigate a cursed house in the countryside, learning the story of the monster that haunts it so he can get a sample of its magic spit.

What could have been a rote collection mission turns into something far more interesting: Geralt figures out what the creature did to earn its curse in the first place. He comes to understand what made the monster a monster. Having done so, he can either cut it down in a straightforward fight or try to solve its problem by, well, sharing a bowl of soup with the beast.

It probably goes without saying that “Blood and Wine”’s approach is a lot more interesting than the alternative.

The design of this mission is a microcosm of what makes The Witcher 3 so special. Though there are plenty of reasons to recommend the game—like its gorgeous landscapes and tense battles—the story is the real draw. The plot in “Blood and Wine” (and the entirety of the Witcher series) is propulsive. It mixes the pseudo-medieval politicking of Game of Thrones with the magic and mythology of The Lord of the Rings, filtering Western fantasy genre traditions through the distinctly Eastern European framework of its Polish creators. And while the grand designs of godlike creatures give the story an epic scale, it’s the cast of characters—human and monster alike—that make the game’s narrative so engrossing.

There’s no shortage of interesting characters roaming the vast environment of Toussaint in “Blood and Wine.” Exploring the streets of its major city, Beauclair, or roaming its fields and swimming its lakes reveals new stories about its people and culture. The game world, like all of the sprawling sandboxes that have come to dominate modern video game design, is filled with one-off missions to complete and special items to find.

But unlike the collectable power-ups and weapons littering an Assassin’s Creed or a Far Cry game, tracking these down isn’t just for those interested in making Geralt more powerful. It’s also worthwhile for players who want to fully discover the game’s narrative. Each pick-up is both an object and a storytelling device. Time spent wandering the world is rewarded not just with useful combat skills and in-game currency, but with introductions to new characters and plotlines.

The Witcher 3 remembers, always, that playing through a narrative-driven game should be a continual act of storytelling. Rather than separate its “mechanical” and “narrative” moments—detaching crucial plot objectives from the time-killing of checking off side missions and collecting pick-ups—it always intertwines them, making sure that something as simple as hunting down an important item is used as a way to enrich the game’s fiction.

When, for example, the player heads out to gather pieces for a set of armor, “Blood and Wine” couples the task with an unfolding short story regarding the person who previously owned and designed the gear. Like many video game expansions, “Blood and Wine” promises powerful new equipment. But unlike in others, tracking it down provides more than just a bump in combat statistics and a shiny new outfit to look at. Piecing together one set sees Geralt exploring a secret laboratory and reading notes that describe a father trying to change his mutated son back to normal; another follows a man who undergoes a spiritual awakening, leaving behind his armor blueprints as he makes a retreat to a cave filled with hallucinogenic gases.

The side missions, too, are filled with memorable storylines. The in-game map is dotted with icons representing new quests for Geralt to take on.

A monster may be roaming the countryside; killing it—and getting some money and experience points for his trouble—requires Geralt to investigate its movements and read up on its biology and weaknesses rather than simply heading to the right area for a quick fight. A city tour guide laments that someone has stolen the carved genitals of a famous statue. There’s no map icon to find the hidden testicles, but a detective’s investigation that ultimately leads to a conversation with a sad old man hoping to increase his libido by owning the famous stones. Even opening a treasure chest, sunk at the bottom of a lake or hidden away in a forest glen, may reward the player with a few paragraphs from a journal entry that reveals how the loot found its way there.

Every one of these optional narrative beats works toward the same goal: making the player believe that the game world isn’t just a collection of artificially designed systems, but a living, breathing space filled with unique people and history. All games are an illusion—a delicate magic act where the audience, if compelled, can forget that they’re interacting with lines of code.

Some are better than others at pulling off this trick, and The Witcher is among the best. CD Projekt RED keeps the player under its spell by refusing to let any aspect of its creation feel like a purely mechanical construct.

This, more than anything else, will be The Witcher 3’s legacy. From the main game through to “Blood and Wine”’s finale, it shows the caliber of storytelling even the most sprawling of video games are capable of achieving. It isn’t willing to settle for keeping its audience busy increasing numbers and checking off boxes by offering endless, hollow “content.” Instead, it features a vast environment and plenty of things for the player to do, because that’s the scale its developer requires to tell a story as wide-ranging and multifaceted as it feels its players deserve.

The “Blood and Wine” expansion for The Witcher 3 is available now.

Reid McCarter is a writer and editor based in Toronto. His work has appeared in Kill Screen, Pixels or Death, Paste, VICE, and The Escapist. He is also co-editor of SHOOTER, runs Digital Love Child, and tweets @reidmccarter.

RELATED: Pam Battles Dark Souls 3’s Toughest Enemies: Other Players