In this trek, the player defeats the Skeleton King, the corrupted spirit of King Leoric who once ruled Khanduras before he was corrupted by Archbishop Lazarus. With the aid of the townsfolk of Tristram, like the sage Deckard Cain along with the witch Adria, the player delves further, defeating many powerful demons such as the Butcher. At length, upon reaching the 16th floor Diablo IV Gold, the participant comes face-to-face with Diablo himself in the bowels of Hell, eventually proving victorious. A cutscene reveals the protagonist taking Diablo's Soul Stone and plunging it. It is unknown at the time he decides to try it, but it is assumed he's corrupted by its existence or is trying to contain Diablo within himself.

The opening cinematic of the game reveals that the protagonist from the first Diablo game called The Dark Wanderer, has lost the battle against Diablo. He seeks to revive the prime evils of Hell, Diablo's Brothers Mephisto and Baal. The participant, working with Tyrael follows in the footsteps of The Dark Wanderer, trying to halt the return of their evils. The player is able to conquer both and destroy their Soul Stones from the Hellforge.

In the growth, the last remaining prime wicked, Baal of Diablo 2, tips Marius to giving him his Soul Stone. This allows him to return to power, and he starts a siege. Though the protagonist was successful, Baal is still capable to corrupt the Worldstone, leaving Tyrael with no other choice but to destroy it.

Following a long wait, Blizzard finally released Diablo 3. Fans discover that there's a 20-year gap between Diablo 2 and Diablo 3, and together with all the three prime evils defeated, the world was in peace. All this changes, however, when a falling star crashes into the old palace in Tristram (exactly the same cathedral from Diablo), also risen dead start pouring out. Diablo 3 gives a great deal of context to the events of Diablo. It's shown that the archbishop Lazarus turned him to Diablo and kidnapped the oldest son of King Leoric. The warrior the player controls during the course of that game is Aiden, the king's youngest son. This means that throughout the class of Diablo, the character has to kill the corrupt soul of his dad as the Skeleton King along with his brother as Diablo.

The player character arrives in Tristram, wanting block the horde of undead from it and to understand the mysteries of this star. After beating the spirit of the previously slain Skeleton King, the protagonist discovers that the fallen star is a guy. It revealed that this man is none besides Tyrael, the Aspect of Justice from Diablo 2 voidk. The remaining angels put him on trial for interfering with the people in Diablo 2, and he cast his immortality to assist the participant ruin evil once and for all. The player then finds that Leah's mom, Adria the witch (out of Diablo), is still living.