“The Lost Souls of Saint Oda’s” is the latest entry in the “Ruby Vaughn Mystery” series by Jess Armstrong, and it’s riveting to the end. This series features the eponymous Ruby Vaughn, a former New York socialite, who was exiled to Europe after a scandal. She volunteered in the Great War and is now living in Exeter, England, running an antiquarian bookshop with her best friend, Mr. Owen. The past six months have seen her solving mysteries with the help of Mr. Owen and Ruan Kivell, whom she met in the first novel. It’s February, 1923, and while the Great War is long over, the shadows of the tragedies endured in that war are still ever-present in the minds of many, including Ruby and Ruan.

This series is definitely one that needs to be read from the beginning to better understand the evolution of the characters, their relationships, and Ruby’s changing attitude toward all things supernatural. Ruan Kivell is a pellar, also known as a witch. In previous novels, he has healed Ruby’s wounds that she received in the course of investigating murders and other mayhem. He also has the ability to hear what she is thinking.

An overarching theme of the novels is the fact that Ruby’s family, her parents and her sister, were killed when the Lusitania sank. In the previous novel, Ruby got a message from someone who claimed that her mother had survived the sinking. Now, Ruby is traveling to the small village of Saint Oda in Belgium, to investigate whether her mother might be the person who was found drifting in the North Sea weeks after the sinking of the Lusitania.

This novel is a bit darker than the previous ones; the danger is apparent from the moment they arrive in Saint Oda. The proprietor of the boarding house they are staying at informs them that it’s not safe to wander at night. “People have a habit of…getting lost here.” And indeed, we soon discover that several people from the nearby priory/psychiatric hospital have gone missing. That’s in addition to the ones who have died, seemingly of natural causes. Several are rumored to have drowned in the lake.

The warning signs are clear: Men talking in hushed whispers about people dying, telling Ruby that she should not be there. Ruby is told that her mother died, and that there was another person who also died that night. But then she meets a strange child, a young girl who drops a small doll and disappears, a small brown hare appearing where she had been standing. We are left to wonder whether the girl is real or a ghost.

There are many characters who all seem to be possible villains, but their innocence is apparent retrospectively when they are killed, almost all in ways made to look, again, like natural causes. And while the murderer must be human, Ruby senses something otherworldly in the air. The mystery is gripping as we realize there is someone besides Ruan with special abilities, but we don’t know who. Ruby herself has some paranormal abilities and has been able to foresee the deaths of people — not necessarily a wonderful gift, but it’s hers. All of their gifts are needed in Saint Oda if they are to find out its secrets. Who is murdering people? Is Ruby’s mother really dead, and if not, where is she? Is the girl Ruby has seen the missing Manon, whose mother drowned in the lake? Or is she, in fact, a ghost?

So many suspects and possible villains make this truly intriguing. The suspense builds and builds and we really don’t know good from evil until almost the very (ironic) end. But it all makes perfect sense, and the ending of this novel will change the trajectory of the future books in the series. In fact, Armstrong provides us with that direction at the end.

For those who enjoy twisty murder mysteries, historical fiction, the paranormal, and tales about family, friends, and romance, this is a lovely series. Armstrong’s ability to create a riveting plot with three quite likable main characters makes this series a favorite. Be sure to read “The Devil in Oxford,” “The Secret of the Three Fates,” and the first Ruby Vaughn novel, “The Curse of Penryth Hall.”

This review was first posted on Bookreporter.com.