"The Hidden Oracle" is the first book in "The Trials of Apollo" series. It features Apollo as a 16 year old mortal named Lester Papadopoulos in New York City, searching for Camp Half-Blood, after being kicked out of Olympus and landing in a dumpster, as a punishment by Zeus for angering him. He must fight Emperor Nero of Triumvirate Holdings and save the Oracle of Dodona with the help of another demigod named Meg McCaffrey who is also the step-daughter of Emperor Nero. It also sees the return of Leo Valdez who was presumed to be dead and was resurrected in the last book of Heroes of Olympus, Blood of Olympus.