His second call was to his attorney, Benjamin Cross. His third was to the head of security at Mercer Ridge Technologies, a former federal investigator named Dana Walsh.

By nine o’clock, Graham was sitting before the home surveillance system. The estate had cameras in every common area except bathrooms and bedrooms. Vanessa knew that; she had approved the system herself.

Graham searched recordings from the previous four months. For nearly an hour he found nothing.

Then Dana called. “Check the kitchen footage from August twelfth at 11:14 p.m.”

Graham opened the file. The video showed Vanessa entering the kitchen in a silk robe. She glanced toward the hallway, removed a tiny bottle with a red cap from her pocket, and approached the blue mug waiting beside the kettle.

Three drops fell into the tea. Vanessa returned the bottle to her pocket and left.