What is the fourth book in the land of stories series?

The Land of Stories: Beyond the Kingdoms

This is assuming you are talking about the series written by Chris Colfer. The books from that series are listed in order below.

1. The Land of Stories: The Wishing Spell

2. The Land of Stories: The Enchantress Returns

3. The Land of Stories: A Grimm Warning

4. The Land of Stories: Beyond the Kingdoms

5. The Land of Stories: An Author’s Odyssey

6. The Land of Stories: Worlds Collide