 Inventor James Frazer thinks his wife Thelma is having an affair, so he leaves for three months to work on his anti-collision device. Thelma and a neighbor, Lois Langley, spend the day together, and Lois spots Thelma romancing inventor Calvin Boone in his office at the firm where James is a partner. Robert and Arthur Hayden, the other partners, announce that if James does not return by a certain date, they will automatically buy his part of the firm, including all inventions, for a ridiculously low price and replace James with Boone. Thelma consults Perry Mason about the partnership agreement. James returns home to find his locked workshop in flames and Thelma dead inside of a gunshot. James arrested for murder and asks Perry to defend him.