Murmurer

Martin decided to step onto the ship. With wobbling ground, he jumped on and started to look it over. Next to where he found Gunder, Martin noticed something. At first glance, it looked like some trash or an odd art piece. But upon closer inspection, he realised that this twisted and dented construct was a gun. Or used to be one. Some older rifle, but it looked like someone sent it through a chopper, bending the metal into a circle-like structure.
Now, Martin finally reached the point of ‘feeling-bit-disturbed’. That feeling one gets in his stomach when something just isn’t right. He turned around looking at the house again. Still no light. If Björn is here, he must be inside. Maybe he can give me some answers. Martin usually does not care about the background of his cases. Results are the only thing that matters. But his curiosity now got the better of him. Some part of him still said ‘Get in the boat and leave, you idiot.’, but he was already on the way to the front door of the house, his hand clenched around his firearm.
He did not take the manners to knock on the door. With a quick bash, he opened the old door. Inside, dust and rubbish. Plates on the ground. Books in the corner. The kitchen seemed to be used recently. Pots were full of stew, still on the fire. The table appeared to be ready for dinner, but no one ate it.
Maybe Gunder was caught off by surprise. In the middle of dinner. Martin noticed two plates on the table. Guests. At least one. Björn? Also, amongst the table laid a thin book. ‘Journal’ it said on the front. Gunder’s name on the first page.
Martin starts to flip through pages. All starting off rather normal. Him and Björn meeting. Spending time together. Falling in love.
But later, something about a message and him leaving Björn to move here. But why?
The latter pages become more distorted, talking about noise from the ground, him worrying about his own sanity. Some ‘Murmurer’ being mentioned several times throughout.
“I dug deep”, Martin read out loud, while pulling up his recorder. “Following the humming. The Murmurer. Clashing metal like lungs. Deep. I found it. Please forgive me.”
Martin swallowed deeply. He took some time to collect his thoughts. “Hermit-Life ain’t easy, but this is nuts. Apparently Björn’s lover lived here. Found the body dead. Male. Middle aged. Light-brown hair. Brown eyes. Man lost it here. Although I’m not sure why yet. Or why he came here. Still no real sign of Björn. Only theories.”
Martin read through the pages again. Some sort of humming, he thought. Martin stood still. Listening. Past the wind outside and his own heartbeat. There! A quite metallic humming. With slow steps, he followed the noise. So quiet, you could almost miss it, but loud enough to never not notice it as soon as you do the first time.
Martin’s ears lead him to a bookshelf. Dirt covered the ground near it. Scrapping-Marks on the wooden floor. Here goes nothing. With all his might, he pushed the shelf along the marks on the ground. Behind it, a tunnel. Tight, but manageable. One last deep breath, and Martin pushed himself through the hole in the wall, down.
For a time, the little pocket flashlight he had was the only source of light in the damp tunnel. The ground was slightly going down, wooden planks gave the walls and ceiling support. The further he got, the louder the humming became. Touching the cold and moist walls, he even could feel the vibration now, coming from all around him. His voice of caution was gone. His mind was silent, only focused on the light the saw before him. With a last step, Martin entered a room.