User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-15110282-20130812002837/@comment-5247339-20130813013235

So it sound like Percy and Annabeth have to find help in Tartarus to defeat the army that guards the doors of death(On the cover it shows one door but I think its meant to have to since its doors) I would guess a Titan like Bob would help them or some friendly monsters.Also Ive been wondering about this for a while what ever happened to Rhea Kronos wife after the 1st Titan war but I can't find anything.Also I think Gaia will kidnap their love ones like Thalia to stop the seven since that seems to be every hero biggest flaw even the demigods.