An unexpected visit to an idyllic wellness center deep in the Mexican jungle turns out to be anything but relaxing in Katherine St. John’s engaging and escapist new novel, THE VICIOUS CIRCLE.

Sveta is a former model stuck in an unhappy relationship with her blue-blooded fiancé, Chase. Shortly after the pair have a potentially relationship-ending fight on New Year’s Eve, she learns that her uncle Paul has died. Paul Bentzen --- known to his devoted followers as Shiva --- was a bestselling self-help author turned spiritual guru who spent his final days at Xanadu, his luxurious, remote Mexican villa. Though they haven’t seen each other in years, he’s left his niece his entire $180 million estate, including all his shares in the valuable Mandala Corporation. Even as Sveta is reeling from her uncle’s death, she can’t help but think about how such an inheritance could change her life. Specifically, it might finally convince Chase’s snooty, judgmental family that she’s not marrying him for his money.

"The appeal of any thriller that takes place in an isolated setting depends in large part on its location, and St. John has chosen hers well. Xanadu is simultaneously inviting and threatening."

A grieving and confused Sveta hops a flight from New York City to Palenque for Paul’s funeral. Along the way, she connects with her uncle’s handsome young lawyer, Lucas Baranquilla, with whom she had a brief fling years ago. Once they arrive at Xanadu, they meet Paul’s enigmatic partner, Kali. She’s not exactly thrilled about being cut out of her lover’s will, though she hides it under an unsettlingly calm facade. Sveta is drawn to Kali, though wary. Lucas sees her as a threat, comparing her to “a cobra, staring into your eyes, ready to strike at any moment.”

The appeal of any thriller that takes place in an isolated setting depends in large part on its location, and St. John has chosen hers well. Xanadu is simultaneously inviting and threatening. It’s the sort of place many would pay good money to visit --- a luxe, lush retreat far from the harsh realities of the modern world, with daily meditation and yoga sessions and a menu of delicious vegan food. But the estate (which was previously owned by a drug kingpin who died in a bloody raid) is accessible only by boat and surrounded by dense forest patrolled by cartel henchmen. It’s also digitally disconnected. Upon arrival, Lucas and Sveta are politely but firmly instructed to hand over their devices in order “keep the energy field pure.” There are other red flags, from the strange tea everyone keeps drinking to the creepy group sex rituals.

Are Sveta and Lucas guests at a hippy-dippy commune, or have they walked right into a cult compound? Unsurprisingly, Mandala --- Sanskrit for “circle” --- is not quite what it appears to be at first. When Sveta arrives in Mexico, she’s in the midst of a personal crisis, and the group’s talk of strengthening the body and purifying the mind has a certain appeal. But eventually the dangerous reality of her situation dawns on her, especially once it becomes clear that Kali is not willing to give up control of all that she and Shiva built to an outsider.

In roughly 300 briskly paced pages, St. John draws a frightening picture of a utopian community spinning out of control. There’s a distinct Jonestown vibe, especially in the way that the presence of outsiders precipitates a major crisis in the group. But she clearly has taken inspiration from several other groups, including the Children of God and the subjects of Netflix’s docuseries “Wild Wild Country.”

As the book races toward its violent climax, some readers may find that a few of the plot twists are a bit too convenient, especially a late-in-the-game revelation about the true nature of Kali’s relationship with one of the other characters. But anyone fascinated by cults and how they operate will find THE VICIOUS CIRCLE compelling reading.