Your protagonist visits a newly opened pub / disco / similar location with friends. There he is approached by a person who behaves a little strange and therefore makes him even more curious. He lets himself be persuaded to have a drink he doesn't know at the bar. Without waking up to what happened afterwards, he wakes up the next morning. It is completely dark. When he tries to touch his head with his hand, he reaches into the void.

Picture: https://pixabay.com/de/photos/cocktail-alkohol-trinken-594173/  

Notes / suggestions:

The text is deliberately vague to give you a lot of freedom. My thoughts on this:

The strange behavior of the stranger. This is not explained in more detail in order not to restrict you. Here you can draw on the full - you can address it as part of the sequel, what this unknown did specifically, or just leave it like that. 

He reaches into the void. You may go in the direction of fantasy or horror - would the drink have done something to him? Perhaps the explanation is also quite mundane - he is still dreaming or is simply too drunk and therefore cannot find his head. Here you could even make a plea against inappropriate drinking.

Or the stranger is your protagonist's future friend and has to get him back on his feet first? 

I am very excited about your lyrics. Suprises me!