In Lies of P: Overture, Black Rabbit Hole Keys are collectible items that help you open hidden doors tied to the Black Rabbit Brotherhood. There are 4 such keys, and each opens a secret door that has unique outfits.
In this article we take you through all the Black Rabbit Hole Key locations and those of the secret doors in Lies of P: Overture.
Black Rabbit Hole Key #1

The first key can be purchased from the Wandering Merchant located in the Carnival Garden area. To reach the merchant, teleport to the Carnival Garden and head inside the Carnival. Once you reach the Carousel, take a left, and you will find the merchant standing in front of the fountain between a wooden cart and a bench.
Black Rabbit Hideout Secret Door #1

After buying the first key, go back to the entrance of the Carnival. Look behind the tent with the sign that says “Clown Knock-Down”.
You’ll find the first Secret Door here. Use the key to unlock it. Inside, there will be a safe that contains the Eccentric’s Mask and the Piercing Death’s Hunting Apparel.
Black Rabbit Hole Key #2

Go into your inventory and equip the Eccentric’s Mask and the Piercing Death’s Hunting Apparel you just got. Once both items are equipped, you’ll automatically receive the second Black Rabbit Hole Key, along with the Brotherhood’s Notes.
Also read: All 8 Gesture Locations in Lies of P Overture DLC
Black Rabbit Hideout Secret Door #2

Teleport to the Eventide Hotel Krat. Go up the main staircase and take the left set of stairs to reach the Miraculous Flower Garden.
Keep going past the black gate in the garden, and you’ll find the second Secret Door. Use the second key to unlock it, and open the safe inside to get the Youngest’s Mask and the Permeating Death’s Hunting Apparel.
Black Rabbit Hole Key #3

Teleport to the Security Area and start from the Stargazer. Head outside and begin dropping down the platforms one by one. Avoid the steam coming from the pipes and take care of the enemies along the way.
After dropping down around six platforms, you’ll find a platform, towards the end, with an enemy walking around. Defeat the enemy, and you’ll find the third Black Rabbit Hole Key in Lies of P: Overture near the edge of the platform.
Black Rabbit Hideout Secret Door #3

Teleport to the Zelator Underground Facility. From the Stargazer, look to your right and go up the stairs. Follow the path ahead, and after a short walk, you’ll see the third Secret Door on your left.
Use the third key to open it. Inside the room, there will be a safe with the Eldest’s Gas Mask and the Black Death’s Protective Apparel.
Black Rabbit Hole Key #4

Teleport to Pistris Harbor. Head down from the Stargazer and take the ladder to reach the lower area. Follow the path, and right when you walk down the stairs, you will come across a mechanism on your left that has a lever you can interact with.
Pulling the lever will cause the submarine to come down and also create a catwalk that you can use to walk across. Right after you cross and take a right, you will find the final Black Rabbit Hole Key in Lies of P: Overture right in front of you.
Black Rabbit Hideout Secret Door #4

Teleport to the Krat Lighthouse and head towards the top of the lighthouse. Once you’ve climbed the ladder and reached the top, head out and walk around until you find an opening where you can drop down to a platform. Once you’ve dropped down, take the ladder to head further down.
Here, you’ll find another ladder nearby, next to a barrel with a lantern on it. Head down the ladder, and right next to it, you will find the final Black Rabbit Hideout’s Secret Door. Use your Key to open the door, and you will find a safe inside containing the Battle Maniac’s Mask and the Blazing Death’s Hunting Apparel.