One of the more difficult missions in The Phantom Pain, “Where do the Bees Sleep” will have you recovering the US military’s new weapon code-named Honey Bee. It’s hidden inside Smasei Fort, but it can be a bit hard to find unaided.
Once you get there, you’ll find a prisoner being roughed up by some Soviet soldiers. You can either fight them or just run away to save time.
You can also use the Honey Bee for this mission, but if you do so you’ll void an optional objective about not using all of its ammo (which will give you a bonus on the final score). Just prime it like any other weapon and shoot the Skulls when they are close together to take them all out.