In a Hail of Bullets was Castle's first bestselling novel, written while he was still at college. It is one of his 'standalone' books, not part of the Derrick Storm series. Although referenced in the show, it has never been made available in the real world.
(From richardcastle.net) Richard Castle’s smash debut novel, IN A HAIL OF BULLETS introduced the world to his electrifying mix of mystery, action, and intrigue. When rookie NYPD detective David McAllister is called to a crime scene on the Upper West Side, he finds a murdered Broadway actress and a seemingly open and shut case. But when the main suspect commits suicide, McAllister senses there’s something going on and refuses to let the case go. As he digs deeper into the murder, McAllister soon finds himself hunted by the most powerful people in the city. He must solve the case quickly – or find himself the latest victim of it.
References in Episodes
Last Call - Castle tells Beckett the book was mostly written in a booth at the prohibition-era bar The Old Haunt.
Biography for Heat Wave; Revealed as Castle's first novel