The 4th book in the Percy Jackson series takes a departure from the central action of the series and focuses on the life-changing events of our characters - what's really shaping who they're becoming. Sure, Kronos is still rising and amassing a giant, angry army to descend on Camp Half-Blood before taking down Olympus and it is what propels our heroes into the Labyrinth but once down there the focus shifts just a bit. We see Grover, who's really under a time crunch, devote himself entirely to tracking down Pan, ignoring the coming doom of Kronos. Percy and Annabeth are really turning into teenagers and those overpowering emotions of first love and utter teenage confusion begin to surface. Even as the end of the world draws near and supernatural creatures start appearing around every turn the human characters still act appropriately human confronting what's going on inside of them as well as what role they'll have to play a demigods.
So, the plot. An entrance to the Labyrinth is discovered on camp grounds and if Kronos' army can navigate the Labyrinth successfully, they can use the entrance to bypass the camp boundaries and invade. Our heroes, Percy, Annabeth, Grover, and Tyson journey into the Labyrinth themselves to attempt to locate Daedalus who they believe is still alive and who can help them learn the secrets of the Labyrinth before anyone else. However, the Labyrinth is an organic place, ever-changing, presenting almost more obstacles than out heroes can survive. This isn't a quest our heroes can beat on their own and outside help comes from other demigods, mortals, Goddesses, and other assorted immortals, but it's the connection our lead characters have with each other that leads to victory. Knowing each other as only true friends can really proves to be the saving grace for all obstacles these guys run into.
One more book to go in this series and I almost feel like Percy's battle against Kronos will be overshadowed by his confusing teenage emotions for his female friends. I really can't decide which story line I'm more interested in reading, but either way book five is going to have an amazing battle to read and, I think, a great conclusion to this wonderful story.