As soon as I finished reading The Lightning Thief (my review), I went straight on and read The Sea of Monsters. This review will contain spoilers for both volumes in the series.
At the end of The Lightning Thief, Percy had rescued Zeus' lightning bolt with the help of his friends Annabeth and Grover. He has learned that it was Luke who betrayed him and attempted to warn the Gods about the threat of Kronos, with no luck. At the beginning of The Sea of Monsters, Percy begins to get strange dreams about Grover and eventually discovers that Grover is being held captive by a cyclops in the Sea of Monsters. Also, the tree that protects camp half-blood has been posioned and the suspicion has fallen on Chiron. The only thing that could save it is the Golden Fleece, hidden deep in the Sea of Monsters. Annabeth and Percy rush to save their friend and their camp, without realising that they might be playing into Luke's hands after all.
The Sea of Monsters is a good sequel to The Lightning Thief, but I didn't enjoy it as much as the first volume. Having since read all five books in the series, it remains my least favourite. It is still very good and still full of Riordan's neat little touches, like locating the Sea of Monsters in the Bermuda Triangle, but it's just not as magical. Although there is a complete adventure in the book, a lot of the plot points are setting up for later events, for example when we find out more about Annabeth, Thalia and Luke, and when we get to see on board Luke's ship. Percy's world is being expanded by Riordan, but we don't get to see the pay-off of this until later in the series.
Having said that, I loved the characters and character development in this novel. Having spent the whole of The Lightning Thief thinking that he was the most important demi-god around and that being a child of the Big Three is extremely rare and special, Percy has to deal with the double whammy of both having a half-brother and the return of Thalia, the daughter of Zeus. His half-brother is a cyclops, which I found interesting, especially as Percy is initially repulsed by this himself. We get to see him mature a bit as he comes to realise that life is much more complicated than a prophecy.
My favourite scene in the novel was when Annabeth and Percy are sailing past the Sirens, and Annabeth wants to hear the Siren song. It's just perfect as it reveals so much about her character, her excessive pride and the way she thinks she can do things better even than the Gods. It's good to see that Riordan is creating flawed characters, even though they are demi-gods. The interaction between Percy and Annabeth in the scene makes their friendship stronger and sets up what will happen later on.
On the whole, The Sea of Monsters is a fun, action packed novel that is still wonderful escapism. I finished the book eager to move on to the next volume in the series.
Source: Personal copy
First Published: 2006
My Edition: Disney Hyperion, 2008
Score: 4.5 out of 5