EverWorld 10 Understand the Unknown

Trapped in an underwater city, David and company must try find their way to the surface. But how can they when the only thing keeping them alive is the tempermental Roman god of the sea, Neptune. Neptune has them in his own little underwater world and the only way for them to stay alive there is for them to make Neptune happy. David doesn't know what to do and to add to his problems Merlin is there looking for Senna. The only thing David knows is that he can't let Merlin get Senna. Also back in the real world he meets that strange lady who told him to "close the gateway" and finds out who she really is. We get to understand David a lot better and see how he is willing to do anything to save Senna and be a hero. Understand the Unknown was a gook book but definitely not the best in the series. At the end we get another cliffhanger and are left to wonder what happens.