The Lightning Thief by Rick Riordan

The Lightning Thief is a 2005 fantasy-adventure novel based on Greek mythology, the first young adult novel written by Rick Riordan. The Lightning Thief is the first novel in the Percy Jackson & the Olympians series, which charts the adventures of modern-day twelve-year-old Percy Jackson as he discovers he is a demigod, the son of a mortal woman and the Greek god Poseidon. Percy and his friends go on a quest to prevent a war between the gods Zeus, Poseidon and Hades.
Rick Riordan finished writing his manuscript in 1994. The Lightning Thief was sold at auction to Miramax Books July 28, 2005.
The Lightning Thief uses some concepts of Greek mythology in a modern setting and is written in a "fast-paced humorous style". Percy Jackson is a twelve year old boy, diagnosed with ADHD and dyslexia, who has been expelled from six schools, the latest being Yancy Academy. During a school field trip to the Metropolitan Museum of Art in New York City, his pre-algebra teacher, Mrs. Dodds, attacks Percy Jackson, revealing that she is one of the three Furies. Percy Jackson's mother Sally allows his stepfather Gabe Ugliano to mistreat them both because Gabe "takes care of them" financially. To get away from Gabe, Sally takes Percy on a trip to Long Island for a three-day vacation.
In the middle of the first night, Percy Jackson's closest friend and former classmate at Yancy Academy, Grover Underwood, who is revealed to be a satyr, warns him that the Furies are trying to kill him ... (Summary by Wikipedia)