They have no choice. If the demigods don’t succeed, Gaea’s armies will never die. They have no time. In about a month, the Romans will march on Camp Half-Blood. The stakes are higher than ever in this adventure that dives into the depths of Tartarus. Quoted from Goodreads
These books just keep getting better and better. It's sort of how this whole Heroes of Olympus series is much better than the original Percy Jackson one. Part of it, I'm sure, is just the author getting better at his craft, but I'll admit, it helps, at least for me, that the characters are a little bit older. It's much easier to take a sixteen year old swinging a sword than an eleven year old. Plus, I love the different points of view.
Okay, we'll start with that. For the first time ever in this series, we get everyone's POV! Yep, all seven characters get their own screen time and character development, and I loved it. It helps that we've had three books establishing these characters, which kept it from feeling disjointed. Plus, as the end nears, each character has their own concerns and obstacles that they'll have to overcome, so it would be hard to skip them here. Really, everyone sort of comes into their own. Sure, they all still have problems ahead, but each character made HUGE strides in this book, ensuring that they'll be the heroes they need to be for the next one.
This book is also exhausting. Rick Riordan is great about giving his heroes a deadline---the world will end August 1st, that sort of thing---which really ups the tension. Plus with Percy and Annabeth in Tarterus, a place where the very air is literally trying to kill them, the clock is constantly ticking. Percy and Annabeth have to escape, the other five have to rescue them, on top of that, their Greek and Roman friends are on the brink of war, all the giants have been freed, and Gaea is about to rise. Part of it goes back to getting everyone's POV. We're always with the most exciting character, so the tension stays high, but still, there's a lot of crazy stuff packed into this book.
Plus, we get some great plot twists. Along with all that character growth I mentioned earlier, we get some great twists I totally didn't see coming but were absolutely justified.
What else did I love? Riordan brings back a lot of characters from his earlier series. I'll admit, there are a few that I didn't really remember. Percy's killed so many monsters it can be hard to keep track. However, the ones he does bring back tend to be the most memorable, and I loved their continued character arc. I won't say much more for spoilers, but I really did love some of the characters we got to see again, especially the ones involved with Percy, Annabeth, and Leo.
Finally, I adore Riordan's dedication page. If you haven't read it yet, this is what he says, "To my wonderful readers: Sorry about that last cliff-hanger. Well, no, not really. HAHAHAHAHA. But seriously, I love you guys." Isn't that great! There are only a few dedications I've enjoyed as much.
If you love the series, this book will not disappoint. It's everything you've come to expect from The Heroes of Olympus series and then some. Everything is bigger, harder, and more personal. It's nonstop action with a serious dose of character development and some humor on the side. Everything is perfectly paced, keeping you turning pages until the end, and what a great ending! Honestly, this is a strong 5 star book, and I can't wait (but at the same time kind of dread, because that means the series is over) for the last book. If The House of Hades is any indication, it's going to be amazing.