The Elsewhere Chronicles.
this is a story about four kids, Rebecca, Noah, Max and Theo discover a passageway into another world, in the abandon house of Granpa Gabe, Rebecca's grand father. The old movie projector in the library opens a passageway to a world of monsters and creatures made of shadows - a place of secrets and dangers set loose when the sun sets. The only weapons to fight them lie in the land of the other side of the shadow door! with Rebecca and Max trapped on the other side of the passageway, Noah and Theo must rush to their aid.