Ronan Boyle Into the Strangeplace (Ronan Boyle #3)

"Ronan Boyle may be the youngest detective of the secret Garda, but now that he's saved the captain from a spooky cult, he's also the only detective that has the head of an old Irish god in his vastsack! But his adventures are far from over. His parents are still on the run (he told them the prison break was a bad idea!), and he still has to turn over the corrupt wee folk to the leprechaun king and return to the Human Republic of Ireland to turn over the god's head"--Provided by publisher.