As Diablo IV is coming and there are important story threads that will be continued after the climactic conclusion of Diablo III. If Diablo IV is going to be your first game in the series then this guide will make sure you enjoy the epic story as much as you can. If you’re a series veteran, then this quick refresher will prepare you for your next visit to Sanctuary.
In the Universe of Diablo, Heaven and Hell were locked in a seemingly eternal war called the Great Conflict. Inarius, an angel, is tired of all the fighting and sets off to find like minded angels and demons who want to abandon the war.
To his surprise Inarius finds many angels and demons sympathetic to his cause and they defected from the Great Conflict, stealing a powerful artifact called ‘The World Stone’ as they left. This World Stone allowed them to create a new place that was neither heaven nor hell, and they called in Sanctuary (this is where Diablo takes place.)
Having fled from the Great Conflict, many angels and demons found they could get along and started families together. The children of an angel and a demon were called Nephalem, they were powerful creatures beyond what an angel or a demon could be. Inarius decreed that the Nephalem must be destroyed, one of his partners Lilith disagreed and wanted to raise the Nephalem as an army to put an end to the great conflict.
In the end Inarius sealed Lilith away in the Void, but never killed all the Nephalem. Instead he used the World Stone to strip their powers, making it so that they would turn into nearly powerless creatures over time. Humans.
This world of humans was relatively calm, and the Nephalem had even helped put a temporary stop to the Great Conflict, but the Prime Evils, Diablo, Baal and Mephisto, were scheming to begin the war again. They were banished to Sanctuary by their underlings and sealed away by powerful agents of the heavens, hopefully to never be seen again.
Of course they were seen again, it’s the plot.
180 years after Diablo was sealed, Leoric arrived in the lands around Diablo’s prison as a uniting king. At the behest of his high priest Lazarus, the king chose Tristram as his capital. What Leoric didn’t know was that Lazarus was a follower of Mephisto, and had convinced his king to choose Tristram because Diablo was sealed under its cathedral.
Quickly the high priest snuck into Diablo’s prison and broke the ‘soul stone’ that bound him. Diablo was now free, but weakened from his imprisonment and without physical form. First he attempted to corrupt and take over the King Leoric, but the king proved too strong to possess. Diablo opted to capture the king’s son, Prince Albrecht, and possess him instead. This action weakened the bond between realms and demons began to attack Tristram as Diablo grew in power.
The player, a powerful warrior, fights their way into the catacombs that Diablo was holed up in, eventually fighting and defeating Diablo as part of the process. Convinced by dark forces that Diablo will escape the soul stone again unless they control it, the player embedded Diablo’s soul stone in their head after sealing him.
Unsurprisingly this doesn’t work.
With the previous hero’s body, Diablo now had a physical form from which to terrorize the land. The previous hero has taken up the moniker of the ‘Dark Wanderer’ and spreads demons and chaos in an attempt to find and release Diablo’s siblings, Mephisto and Baal.
It’s worth noting that, unlike Diablo I which has a canonized hero (the warrior) Diablo II is technically canon no matter which of the 7 classes you play as.
The player in Diablo II chases after the Dark Wanderer, but only catches up with them after they have released the prime evils. The player is able to slay Mephisto and seal him in the Black Soulstone but Diablo escaped into hell. The player follows.
Deep in the pits of hell, the player is able to summon Diablo when he is not fully recovered from his time in Sanctuary. There is a brutal fight, but the demon is defeated. He is sealed in the Soulstone.
Later in an expansion, Lord of Destruction, Baal attempts to corrupt the Worldstone so that he may use it against the High Heavens. After the players defeat Baal, Tyreal, the Aspect of Justice destroys the worldstone, which exposes heaven and hell to sanctuary.
Baal is sealed. Additionally two of the other lesser evils are trapped in the stone during this game, but they are mini bosses.
With the Worldstone gone and the spell that weakened the Nephalem gone with it, the next generation of humanity contains some Nephalem. The player is one of these powerful heroes.
The player arrives in New Tristram to investigate a falling star that landed in the Cathedral. Fighting their way to the bottom of the cathedral they found a man was the falling star. Confused but determined, the player sets out to find answers.
After collecting pieces of the mysterious man’s sword and returning them to him, his memory returns. He is actually the Angel Tyrael, the Aspect of Justice. After seeing how unwilling the heavens were to help humanity in Diablo I and II he relinquished his divinity to fall to Sanctuary and warn humanity of the coming threat. Two of the lesser evils were on their way. Belial, Lord of Lies, and Azmodan, Lord of Sin are coming to Sanctuary.
The player, Leah (a half-witch from Tristram) and Tyrael (as a mortal) set out to find the Black Soulstone, the same one that has 5 of the 7 evils within it. A powerful Witch (and Leah’s mother) Adria tells them how and where to find it. They are able to get the stone, but not before Belial has caused mass chaos within the city of Caldeum.
After a long and brutal battle, the player and their crew of followers are able to defeat Belial and seal him into the Black Soulstone. They head to Bastion’s Keep to track down rumors of Azmodan.
When they arrive at the keep it is already under attack by Azmodan and his demonic forces. Through a brutal siege, the player is able to seal Azmodan within the Black Soulstone and Tyreal convinces the player to bring the Soulstone back to Adria, who can hopefully destroy it and all the great evils within.
Adria reveals that she’s been working for Diablo. Her husband and Leah’s father was the Dark Wanderer and she just needed you to get the final souls. Adria unleashes Diablo with the souls of all the evils within him, using Leah as a conduit. Diablo is now the Prime Evil and begins his assault on the heavens.
The player arrives in the High Heavens and is able to stop Diablo before he reaches the crystal arch and destroys the power of the Heavens. Diablo is sealed in the Black Soulstone once again by the player. It falls from the High Heavens and ends up back in Sanctuary.
Tyrael claims a new spot as part of the heavenly host, but keeps his humanity to try to create a bond between the High Heavens and the new Nephalem that saved them.
Tyrael sets upon trying to seal the Black Soulstone but is attacked and injured by the former Archangel of Wisdom, Malthael. Malthael has set out on a quest to destroy all of humanity as he sees them as remnants of their demon parents and is convinced that the Great Conflict will never end as long as they are around.
Using an army of renegade angels and spirits, Malthael attempts to use the power of the Black Soulstone to destroy all of demon kind, but the player stops him in order to save humanity. The player battles Malthael and defeats him, but not before Malthael absorbs the powers of the 7 evils. This means that killing Malthael releases the evils once again.
There has been one Cinematic Trailer for Diablo 4 so far. It heralds the return of Lillith, mother of the Nephalem and the main antagonist of Diablo 4. You can check it out for yourself here.