After a tornado rips through the southeast of England, Leo must journey to another world in search of his brother who is amongst those who have disappeared.

This search takes him to Libero, a world that was created by four people with the ability to control the elements as a place for people to find true freedom. But even freedom comes at a price. For in this world, the animal instinct that lives within you will develop the longer you are there, and so it is a race against time for Leo and his friends to rescue his brother and return home before it is too late, before they become part of the instinctive.

If you choose to come, know your life will never be the same,

You leave behind your old self, all that will remain is your name.

You will learn what you were born to be,

Who you truly are, beneath what the eye can see.

Come for the people, Leo, come for your brother,

Leave behind what you think you know, Leo, expect a place like no other.

For in Libero, Leo, you will find everything you think you lack,

So be warned, for when you find Libero, Leo, you may not come back.

Michael Rowley (editor of The Martian, The Bear and The Nightingale: Winternight Series, and After Earth) compared Instinct to The Lord of The Flies, The Wonderful Wizard of Oz, Peter Pan, and The Island of Doctor Moreau.