The Son's Secret by Daryl Wood Gerber

What if you're the only one who believes your son is missing? A chilling, twisty psychological suspense novel, perfect for fans of Laura Dave and Gillian Flynn.
Maggie Lawson is the smart, capable dean of a boutique college, but even the most confident mother has a weakness - her child. When Maggie can't reach her college senior son, Aiden, to tell him that his father has been shot, she starts to panic. She texts. She calls.
Is Aiden ghosting her, or have the dangerous stories Aiden's father, her investigative journalist ex-husband, pursues finally brought trouble to her door? Maggie is sure that something is very wrong, but no one believes her. As dark events unfold, she must rely on her own investigative instincts to find Aiden. But when Maggie uncovers a devastating secret, she faces a race against time to save him.