From the back of the book:
When an easy job turns into a fight for survival... Who would have guessed that this small valley at the edge of the kingdom was harboring a power able to force the doors of time wide open?
Tahenn Pass is a small anonymous vale, lost in the Drakenbergen. Undertaking an apparently ordinary mission, the adventurers will delve into an ancient ruin containing the mysterious and powerful Chronolith. There a temporal catastrophe will give the adventurers more than they bargained for and lead them to explore both the geography of this region and its various epochs!
The Chronolith is an adventure for characters of levels 1-5 taking place in a valley of the Drakenbergen. It is powered by the rules of the 5th edition of the most mythical role-playing game. Written by Eric Nieudan, this module has been designed to be played autonomously, sandbox-style, offering great freedom and many possible twists.