A decade ago, two vans filled with high school seniors on a school service trip crashed into a Tennessee ravine, which claimed the lives of multiple classmates and teachers. The nine students who managed to escape the river that night were irrevocably changed. A year later, after one of the survivors dies by suicide on the anniversary of the crash, the rest of them make a pact: to come together each year to commemorate that terrible night. But by the 10th anniversary, Cassidy has worked to distance herself from the tragedy. This year, she is determined to finally break ties once and for all. But on the day of the reunion, she receives a text with an obituary attached: another survivor is gone. Now they are seven, and Cassidy finds herself hurling back toward the group, wild with grief --- and suspicion.