What the Pressure Kept

You are Noa Veth, deep-ocean courier, and your submarine — the Silthorn — has been sitting silent on the seabed for six hours. The mission: deliver a sealed diplomatic envelope to the surface relay before the tide window closes. But when you reached your post in the control room you found the helm vacant, the navigation console dark, and a single ice-cold canister blocking the helm seat. Somewhere in the stillness, the Silthorn is keeping a secret that the cold has locked away.