The Grey Knights is a secret chapter of Space Marines trained to hunt down and exterminate Chaos Daemons. Each Grey Knight must undergo an incredibly gruelling selection process, and training that borders on torture. They are armed to the teeth and bio-engineered beyond a regular Space Marine. Their psychic abilities are surgically enhanced so they can harness the power within the Warp as a weapon against the Daemons. Their existence is thought of as a myth to many, but the truth is closely guarded knowledge among a very select few.