The Trials of Apollo

The Trials of Apollo is an American children's fantasy action-adventure middle grade children's fiction book series based on Greco-Roman classical mythology, written by American author Rick Riordan. It is the third of four book series in the Camp Half-Blood Chronicles, succeeding Percy Jackson & the Olympians and The Heroes of Olympus, and preceding The Nico di Angelo Adventures. A supplementary book, Camp Jupiter Classified, has also been released in addition to the main series.