The Tyrant's Tomb

The Tyrant’s Tomb is the fourth book in The Trials of Apollo series. It is set to be released Spring 2019. This book will follow the Erythraean Sybil Herophile's prophecy (from The Burning Maze): "Apollo faces death in Tarquin's Tomb unless the doorway to the soundless god is opened by Bellona's daughter." This further makes it certain of the appearance of Camp Jupiter heroes in this book, especially their senior Praetor Reyna Avíla Ramírez Arellano, Bellona's daughter.

Development
In a interview, Rick Riordan stated that the book will have Camp Jupiter, Hazel Levesque, Frank Zhang and Reyna Ramírez-Arellano. This book will not only follow the new prophecy as issued by the Erythraean Sybil, but will also complete the final stanza of the previous prophecy from Trophonius. Also, the Sybilline books from the Cumaean Sybil is the next source of prophecy that should be freed, before the final one, i.e., the Oracle of Delphi (as mentioned by Apollo in The Burning Maze). The Sybilline books are being reconstructed at Camp Jupiter with the help of Ella the Harpy.

Trivia

 * In Rick Riordan's The Ship of the Dead tour he announced that Camp Jupiter will appear in this book.
 * Tarquin was the last of the Roman Kings, before Rome became a Republic.