Remain Calm is One Creepy Horror Story
This story hinges on a joke everyone has lived. Tell someone to remain calm and they immediately start scanning for the reason not to. The premise weaponizes that reflex, making your own panic the monster in the room. A federal agent who smiles and gives you the one instruction your brain is physically incapable of following, that is a horror setup I can get behind.
I keep thinking about the times a dentist or a highway patrol officer has told me to calm down and how my heart rate doubled on the spot. The story turns that universal cringe into a survival mechanic. Usually horror rewards the runner, the fighter, the one who hits back. Here the only winning move is steady breathing, which is probably the last thing anyone manages in a crisis.
I would want to know whether the agent senses fear or whether something worse triggers when you break. The description cuts off right as it asks what normally calms you down, which suggests the story is pointing at mundane coping mechanisms as genuine lifelines. That grounding makes it work better than another monster with teeth.