I find that there is no better way for characters to set out on an adventure than to journey though a mysterious forest - or any forest for that matter. J. R. R. Tolkien's The Fellowship of the Ring - following the inciting incident - has the Hobbits journeying through a forest when the Ring Wraiths come looking for the ring.
A forest is a great source of atmosphere, so many things can realistically happen in a forest that your story can be out of this world and relatable at the same time. Fog can roll off a nearby river or stream, monsters can be hidden in its shadows, the trees can be alive with the creatures crawling across their limbs.
To create a forest that can harbour a story that is full of suspense. Adjectives are going to be crucial in this challenge as it is the descriptive power of words that give your creations their feeling.
Signing off for now,