That Night by Gillian McAllister

Three fiercely loyal siblings make a split-second decision to cover up a deadly late-night accident, binding themselves to a secret that quickly spirals out of control. As the lies mount and anonymous threats close in, their once-solid family bond fractures under guilt, suspicion, and long-buried resentments, forcing each to confront how far they will go—and what they are willing to sacrifice—to protect one another.