"Impostor: An Alexander Gregory Thriller" by L. J. Ross is a gripping mystery novel set in the United Kingdom. Published by Sourcebooks, Incorporated in 2026, this first edition trade paperback is part of the Alexander Gregory Thrillers series. With a narrative that keeps readers on the edge of their seats, this thriller is perfect for adults who enjoy crime fiction. The book features 320 pages of suspenseful storytelling, making it a must-read for fans of the genre.