There are several quest missions in Gray Zone Warfare and numerous stories to discover as you explore each part of the map on Lamang Island, including the story behind Gunny's Unnameable mission.
UNLRA | Handshake | Gray Zone Warfare GUIDE | Fast/Solo | Mission Tutorial
Unlike other searches, the Unnameable search requires you to find a missing UNLRA employee who was sent on an expedition into the jungle for the organization. He was likely working near Ground Zero, but his family knows he was not staying at the UNLRA main camp. He said he was staying in a room near Tiger Bay Central and complained about the smell of fried seafood in a restaurant.
There aren't many clues as to his position, but here's how to find the staff member in the Unnameable Mission in GZW.
To complete the Unnameable quest in GZW, head to Tiger Bay and find your way to the restaurant in the small town marked on the map. The house you need to enter is the second house from the road and should have a couch in the middle of the room on the first floor, three plant pots in front of it, and a blue fridge.