Three months ago, Lena Nguyen's estranged twin sister drove to a remote bridge in Montana, exited her car, and jumped two hundred feet to her death. She left behind a vague suicide note and no answers. Lena suspects murder. Armed with an audio recorder, she travels to that very bridge to interview the highway patrolman who allegedly discovered her sister's body—and maybe catch him in an incriminating lie. But as her twin's final hours come into focus, Lena's search for the truth turns into a harrowing, tooth-and-nail fight for her own survival—one that will test everything she thought she knew about her sister, lest she join her at the bottom of the valley.