The Deadly Truth by Helen McCloy

Doctor Roger Slater was a chemist who was developing a truth drug for the Sutherland Foundation. This drug, novopolamin, was designed to be used by the police and had fewer side effects than other similar drugs on the market. He was working on this when beautiful Claudia Bethune stopped by his lab to invite him to a weekend party at her home. Roger was quite smitten with Claudia and could not resist telling her about his new discovery and showing her the pills. After Claudia had left, Roger discovered that one tube of pills was missing and that Claudia must have taken it. He went chasing after her.

Claudia was noted for her unusual parties. For this weekend, those present were Michael Bethune, her husband, and Phyllis Bethune, Michael's previous wife. Charles Rodney was there. He was the head of a textile mill of which Claudia was a majority shareholder. Young Peggy Titus was also invited. Basil Willing was there for a short time. He was a psychiatrist who was renting a summer cottage, the Hut, on Claudia's property. Basil left before the evening party began.

Roger Slater begged Claudia to give the pills back to him. If the Foundation heard that she had taken the drugs, Roger would lose his job. Claudia denied knowing anything about the pills. When cocktails were served to the guests, Roger knew that they had been drugged. He and Claudia didn't drink anything but the other guests did. The truth serum began to take effect and some really disturbing truths came out over dinner.

Much later that evening, Basil Willing noticed one light on in Claudia's house, worried that something was wrong, and walked over to take a look. When he looked in the window,  he saw Claudia sitting dying at the table. Basil could see nobody else, but heard footsteps in the room. The murderer was still in the room, but when Basil accidently made a noise the murderer fled. Basil entered and saw that Claudia had been strangled with her very valuable necklace.

Basil Willing's position as psychiatric consultant to the Attorney General's office and his proximity to the scene of the murder led to him being closely involved in the hunt for the murderer. It was apparent that the murderer was one of the people at the party, and Basil investigated their present activities and also their pasts. He found that some of the suspects had worked hard to cover up their past activities.

At the end of the book, Basil gathered all the suspects together, and presented his findings, and named the murderer. The reader will see that all of the clues have been given in the course of the book so the author has played fair with the reader.

I found this to be a very enjoyable and well written book. Helen McCloy published this book in 1941. It was the third in the series of 13 books which featured Basil Willing. E-book editions of her books have been published by Orion.