The comic's central subject is the power known as The Darkness and its wielders. The Darkness is an ageless power dating back beyond human history. It is linked with the Angelus and the Witchblade. The Darkness is passed down a family line from father to son, leaving the previous user (and taking his life) as his first child is conceived. The power then manifests in the child on his 21st birthday.
Darkness users can create anything they desire with The Darkness, even sentient beings, but anything they make will crumble to dust in the light. The Darkness is quite deadly, allowing the user to call forth darkling minions to aid them, and even survive gunshots. The power can also be used to maul and feed on people.
The Darkness does not function unless it is dark, but some users can also manipulate this by creating their own shadows/darkness (e.g. smoke grenades), being underground, turning off lights in a room, etc.