Our story begins 10 years after the events of Doom II. Earth governments try to recompose the remnants of civilization after the war with demons.
Meanwhile Cabal co. remained latent, waiting for the right moment to be able to take over the old laboratories of the UAC. The goal of Cabal co.
is to build its own portal generator, for the sole purpose of not only bringing back all Cabal co. members who fell in combat against Caleb, but also Tchernobog himself.
Infiltrated in the abandoned installations of UAC, Cabal Co. tries to use their portal tech to bring back Tchernobog and all fallen soldiers and demons.
This time arcane magic and UAC tech wasn't enough, they not only opened again the Doors of Hell, in addition merged present time and the past in a whole same universe called the Void.
During the process of opening the portal, the Cabal's engineers detected an anomaly surely due to a bad adjustment of the collider.
This produced a space-time disturbance in which world from past times (Blood) merged with the present time (after Doom II).
And not only that! They also brought back to life all the acolytes of Cabal along with the demons of hell slaughtered by Doomguy.
The Cabal forces can't control the Icon of Sin and their demons, so they decided to use a variation of the portal now to mix members of Cabal with the Demons from Hell, summoning then unthinkable abominiums called Hybrids: fierce and strong as hell demons and so obedient and violent as a Cabal follower...
Luckily on this occasion Doomguy will not be alone, the fusion with the world of the past brought an ally, Caleb.
Together they will not only fight to destroy the demons and acolytes of Cabal, but also the secret weapon of Cabal, the hybrid creatures!