WHAT'S NEW

“Lost in the Valley of Death: A Story of Obsession and Danger in the Himalayas” by Harley Rustad (Harper/harpercollins; 304 pages): In August 2016, an experienced American trekker named Justin Alexander Shetler embarked on an expedition in the Parvati Valley of northern India, never to be heard from again. Rustad’s tense, fascinating book about his life asks what draws people to danger.

“The Berlin Exchange” by Joseph Kanon (Scriber; 320 pages): When nuclear physicist Martin Keller is freed from a U.K. prison and returned to East Germany in a 1963 spy swap, he’s happy to reconnect with his terminally ill ex-wife and their 11-year-old son, a popular actor on a hit TV show. But Keller soon comes to loathe the police state demanding that he build East Germany’s first atomic bomb.