Watch Me Disappear by Janelle Brown

Jonathan and Billie are the perfect couple. They met on public transit, fell in love at first sight, and got married on a beach two weeks later. Nearly two decades later, they have a house in Berkeley, an environmentally-conscious teen daughter, and a seemingly perfect life. Billie is a stay-at-home mom who loves yoga and hiking, and Jonathan has worked his way up the ladder at a tech magazine. But their perfect life comes at a price. Jonathan is a workaholic, and Billie, a wild child in her youth, begins to grow bored and disillusioned with their life together. So, Billie decides to take a page from Cheryl Strayed's playbook and hike out her problems solo on the Pacific Crest Trail. Instead, she vanishes on her hike, leaving behind only a lone boot.

A year later, with Billie close to being declared legally dead, their daughter Olive begins to have hallucinations (or are they visions?) of her mother, very much alive. As Jonathan and Olive begin searching for answers, they find a tangle of secrets in Billie's past that makes them question everything about the woman they loved and thought they knew.

Janelle Brown weaves a compelling, twisty tale that will keep readers turning the page and guessing right up until the last sentence. A great summer read, perfect for fans of Gillian Flynn's Gone Girl.