<p>Three days of rain turn a quiet Missouri spring into a crime scene when human remains surface from the limestone depths.</p><p>Forensic investigator Dr. Cassian Holt and K9 handler Jonah are called to Ozark Springs State Park where the evidence points beyond one body and into a hidden underground disposal operation. Chemical traces deep-cave water patterns missing workers and ignored disappearances begin to form a chilling map of exploitation corruption and murder.</p><p>As the Critical Trace team follows the case into flooded passages and industrial cover-ups Cassian and Jonah must balance professional precision with a relationship already tested by fire danger and trust. Their bond is no longer a secret between cases. It is the force that keeps them moving when the investigation descends into darkness.</p><p><em>Limestone Nightfall</em> is a thriller-forward MM romantic suspense novel for readers who want forensic investigation dangerous settings protective partnership found-family teamwork and a mystery that reaches from rural cave systems to corporate power.</p>