From the opening paragraph, Peter Stamm's "To the Back of Beyond" is mysterious and mesmerizing.

Thomas and Astrid are in their back garden at the end of the day, at the end of summer, at the end of vacation. When Astrid goes into the house to tend to their children, Thomas stands up, moves to the gate and, "with a bewildered smile that he was only half aware of," walks away. He does not come back.

Many novels have sprung from the premise of a spouse walking away from a marriage, but Stamm's take is entirely original. Thomas never planned to leave. He loves Astrid and the children, and it is his thoughts of them that sustain him, keep him warm, during the next few weeks or months as he trudges deeper and deeper into the Alpine wilderness.

The book moves smoothly between his point of view and Astrid's, so skillfully that this inexplicable adventure seems completely plausible. Thomas hikes through forests and up mountains, sleeping rough, foraging for food, occasionally finding shelter. He knows where he is headed, although we do not.

At home, Astrid comforts the children, imagines Thomas on his journey, sets out to find him. She is baffled, but not angry. Somehow she understands this is a journey he needs to take.

Stamm's pivot halfway through the book is masterful: The story opens up, moving forward and backward in time almost simultaneously. The outcome becomes murky, but Stamm's control never wavers.

"No one seemed to understand that her relationship with Thomas wasn't over just because he wasn't around anymore," Astrid thinks. And that might be what makes this strange, lovely book not a story of loss or grief but a hopeful story of profound love.

Laurie Hertzel is senior editor for books at the Star Tribune. @StribBooks

To the Back of Beyond
By: Peter Stamm, translated from the German by Michael Hofmann.
Publisher: The Other Press, 140 pages, $15.95.