User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-1515612-20130507150820/@comment-3146930-20130511030801

Well, going by what we know the ultimate goal of this book will be to make it to the Doors of Death inside the House of Hades. Percy and Annabeth are trapped in Tartarus and the rest of the crew has to fight Gaea's forces on the Mortal side so they can clear the way for Percy and Annabeth. So here is what I'm thinking:

The Argo II floating up in the sky, with the ship being attacked by an army of monsters below and Festus breathing fire. Smaller monsters are climbing over the sides while Jason, Nico, and Frank fight them off. Down below is the entrance to the House of Hades being guarded by a Gigantes.