Heroes of Olympus
The Heroes of Olympus is a sequel series to the Percy Jackson & the Olympians series, written by American author Rick Riordan.

The series revolves around a prophecy that was introduced in the last book in the Percy Jackson series. The prophecy states that seven demigods would unite to protect the earth from Gaea. in Greek Mythology, is the personification of the Earth but in this series,is out to destroy the Earth.

The main characters from the original series, Percy Jackson, Annabeth Chase and Grover Underwood, are joined by Greek demigods Leo Valdez, Piper McLean, Nico di Angelo and Thalia Grace, Roman demigods Jason Grace, Hazel Levesque, Frank Zhang and Reyna Avila Ramirez-Arellano and Percy’s half-brother Tyson, a cyclops. The series includes five novels, of which the first, titled “The Lost Hero” was released on October 12, 2010 followed by the second book “The Son of Neptune” in October 2011. A third novel, with the title of “The Mark of Athena” was released in 2012, which was followed by “The House of Hades” in 2013 and the final book of the series, “The Blood of Olympus” in 2014.

The Demigod Files
The Demigod Files is the first companion book to the Percy Jackson & the Olympians series. It was published on February 10, 2009 by Disney Hyperion. The book includes three short stories, namely “Percy Jackson and the Stolen Chariot”, “Percy Jackson and the Bronze Dragon” and “Percy Jackson and the Sword of Hades”, a preview of “The Last Olympian”, crossword puzzles, interviews with the campers, such as Percy Jackson, Annabeth Chase and Grover Underwood to name a few and portraits of the characters. The three short stories take place between the fourth and fifth books of the Percy Jackson series, “The Battle of the Labyrinth” and “The Last Olympian” respectively.