The one who walks with death

A Journey Between Dimensions of Supernatural Beings

A fantasy about an ageing detective who discovers a world of the bizarre entity Death and other supernatural beings. The world around us is not just what we see before our eyes. Certain layers remain hidden from us mortals, until a specific moment. The world of Death and the dimensions of many other supernatural beings, who are here to serve us, weave through them like a snake.
Detective Sam would add that this is utter nonsense. He doesn't think the service of Death is something we particularly need. Death herself would probably point out that people have to die, but Sam sticks to his guns. Their bickering relationship-non-relationship sets in motion the plot of this paradoxical story, where a closed-off, introverted, grumpy human being meets the talkative, curious, and almost bossy Death, who has a weakness for Cabernet Sauvignon.
How did these two actually run into each other, and why must they spend time together?