The end of the Mark of Athena

The ending is really great but it is a leaves you hanging on a really big cliff literally. Percy and Anabeth are falling in a pit falling into Tarterus the land of dead monsters, and titans, and the worst of the worst from Greek mythology. The next book in the series is called The HOUSE OF HADES. I think what will happen in this new book is that they will close the doors of death, and Gaea will come harder, and faster then ever cause she is ready to stop the hero's of the story.