Cora Buhlert 
Spelunkers [EPUB ebook] 

During a holiday in Belgium, college students Evan and Matt decide to explore an uncharted cave in the Ardennes. Also along for the ride is Evan’s sister Kate, who has been tasked with looking out for her brother since early childhood.
Deep inside the cave, Kate, Evan and Matt stumble upon a portal to another world. But does this portal represent the greatest adventure of their lives or a terrible danger…?
This is a science fictional tale of terror of 3800 words or approximately 15 print pages by Hugo finalist Cora Buhlert.