The Shoot From Hell

The movie stuntman's fall on the set kills him, making his insurance beneficiaries-three people-wealthy.  The detective discovers the Hollywood director's previous shoots have been plagued with "accidents."  He's killing stunt men to collect their insurance? The female private eye shadows suspects who are losing their grip on reality, scared that she knows what happened and how.  So why doesn't she pounce?  Because she's merciless, unconventional and forces perpetrators to break down and incriminate themselves.
She's running lab and field tests on props and equipment because the murderer used high-tech materials to rig a foolproof accident.  Inciting mistrust, she's turning the suspects against each other.  Bombarded by the PI's ambushes, the trio can't work.  So they cover up the evidence-try to, for the investigator anticipates the maneuver.  She's not surprised by who shows up as the killer-but readers will be, and relish the war of nerves.