Don't Open The Door by Allison Brennan

A child is shot while playing video games at home. His mother will stop at nothing to find out who did it—and why.

After their ten-year-old son, Chase, was senselessly murdered, Regan's life unraveled. Her corporate lawyer husband, Grant, blamed the death on Regan’s work as a US marshal. Unable to reconcile their grief, they divorced, and Regan quit her job and moved away.

Now she's back after a voice mail from her former boss Tommy said he had important news to share about Chase’s killing. Regan is stunned to learn Tommy is dead too. When she reaches out to Grant, his panicked reaction raises her suspicions. Then a lawyer with ties to her ex also turns up murdered, and the police make Grant their top suspect.

Unsure of his guilt or innocence, Regan risks everything to find Grant before the police do so she can finally get the answers to all that has haunted her since losing Chase. But the truth is not even close to what she imagines—and now she fears she has no one to trust.