Hidden within Prey is an optional quest that really rewards the obsessive completionist gamers. Hidden in the game are four treasure maps that were given to a group of people involved in a game of Fatal Fortress – Danielle Sho, Zachary West, Elias Black, and Emma Beatty. Here's how you can find it.
First, to initiate the Prey side quest, head to the Crew Quarters and investigate Danielle Sho's computer. You should find an email called "Treasure Hunt." Open it to receive the objectives and begin the quest. Gamemaster Abigail Foy handed some of the maps to the players in person, while others may have files on their workstation. Either way, you must find all the files.
First, you must find Zachary West's map. Known as the Hordinbaffle Flagdastreous Map, it can be found in the Arboretum, which is near the airlock on the first floor. Take the Deep Storage elevator from the main floor to reach the location and you'll find Zachary West's body. Loot the body to retrieve the map, where a diagram of a room with three circular objects in the middle is revealed.
The diagram is identical to the blueprint of the water treatment facility located on the second basement level. The arrow in the diagram will point to a number three on the wall. Zoom in on it to register the clue in your quest log.
Next, you must find Emma Beatty in order to obtain the Rosalyn Swyft's Treasure Map. Head back to the first level of the Crew Quarters to find her. And while she's not dead, Emma is mind-controlled, so you may end up having to kill her anyway.
The clue on the Rosalyn Map will take you to the Cargo Bay. Head to the GUTS loading bay on level 1, which is located on the southwest corner of the map. Near the container, you'll once again discover a number five on the wall. Zoom in to scan and register the number clue into your quest log.
The map that belongs to Elias Black can be found in the level 2 recreation center inside Crew Quarters. Find the Captain Stabfellow Map on a large table with a giant Fatal Fortress screen above. The map is next to a Captain Stabfellow character sheet.
The map will direct you to the recycler room, which is also on level 2 of the Crew Quarters, west of the Yellow Tulip. You will find a large number six on the wall. Once again, scan and register the number clue to your quest log.
Finally, Danielle Sho's map can be found at her workstation in level 2's Deep Storage. However, you will have to get past a thermal phantom and a couple mimics before you can reach the command center. A handy turret is available to help you take them down.
The Melindra Shadowcorner Map will point you to the G.U.T.S. Go to the Fuel Storage next to the Shuttle Bay entrance and elevator. Find the number one and zoom in to scan and register it to your quest log.
So there you have all four numbers necessary for the combo. However, Prey guides and player feedback suggest there's more than one combo to the puzzle. You'll have to shuffle the numbers around with a bit of trial and error before you can find the right combination to unlock the reward in Abigail Foy's room.
Lastly, for the casual Prey gamers that stumbled across this guide with mild curiosity, do not try to solve the 4-digit combo without solving all treasure maps first – the game will penalize you for cheating by implementing a debuff that greatly reduces your crawling speed and the intensity of your flashlight.
Check out the gameplay guide for the Prey treasure hunt in the video from YouTube channel NamelessDreadx37x below: