What? You need more detail? The Aztecs and hook-handed adventuring not enough? It is good fun, with sympathetic characters (even the turncoat Aztec spy is likeable), with plenty of exciting twists and turns. Just read it.
Like all the Tor freebooks it sets up a whole series of sequels (damn their clever marketing ploy! They've snared me good!), and I'll be keeping an eye out for the next one: "Ragamuffin".
Good job, Mr. Buckell. Carry on.