Beck Granger is the fearless main character who always seems to know what to do when things go wrong.
And that's good news for his two new best friends Marco and Christina - a brother and sister who have a lot to learn about survival skills.
There's also Beck's Uncle Al, Marco and Christina's dad Mayor Rafael de Castillo, and creepy police chief Ramirez.
Uncle Al takes Beck with him on an expedition to Columbia, to help Marco and Christina's dad search for the lost City of Gold.
But when the adults are kidnapped, it's left to Beck and his new friends to solve the mystery on their own.
As Beck leads them into the Columbian jungle, their mission develops into a dangerous race against time to find the ancient city and rescue his uncle and the Mayor.
Things go from bad to worse as the trio face broken rafts, shark attacks, hungry wild animals and more. Will any of them make it out alive?
Beck's adventure with Marco and Christina really is action-packed and zooms along so quickly you'll be out of breath just reading about it!
There are loads of survival tips to pick up along the way too, although they can be a bit gruesome at times... Anyone fancy drinking a fish eye?
Then again, you never know when you might be grateful for the knowledge that you can use the oil from a fish liver as sun cream!
Any weak bits?
The beginning seems a bit confusing at first, but it's worth sticking with it to get to the action bits!
After you've got through the first few pages, you bet! It will really keep you guessing.
This reviews page is now closed. Here are some of the reviews you sent in.
"A brilliant book. I let my gran read the blurb and she thought it was so good she wants to read it!"
Joseph, 10, Kent, England
"I understood the story but I got really bored about halfway through and stopped reading it. It seems a bit childish as well, with lots of simple words."
Damien, 11, Cambridge, England
"I bought it yesterday and finished it yesterday! It's really interesting and tense. I'm definitely going to read it again today!"
Tiya, 11, London, England
"Brilliant book, you can't go wrong buying it. You really get your nose in it."
Finn, 10, Exeter, England