The Trials of Apollo - Rick Riordan+2
Rules Are Made To Be
by Emightbemypenname
Three months after his return to godhood, while Apollo is taking the sun chariot through a merry ride over Ireland, he is attacked by a mysterious group of creatures. When seeking out more information on the species his questions are blocked at every turn. He starts digging for more information on the species that his father forbade him from seeking out, but realises too late that he should have stopped digging, when a prophecy is foretold that whatever those things were, they were going to spell the end of Zeus' rule on Olympus and that he was going to help them.