A Dark Place is a forest located in the Shadowlands inhabited by Soul-Eaters. Here, the barriers between the realms of life and death are thin, and spill over into Azeroth. It can be reached by interacting with a Shadow Tear at in the eye socket of the skull of a green dragon at the Emerald Dragonshrine in the Dragonblight after completing the chain up to this point. This is where the eredar child Uuna was saved by an adventurer.
The only light in this dark place is you!