Champagne for One

Everyone who knew Faith Usher knew she always carried a bottle of poison around with her, so when she dies after drinking champagne, everyone from the police to her friends to the father of her child assumes she killed herself. Nero Wolfe's ace assistant Archie Goodwin is the only one who insists it was a murder. As the portly detective investigates, all the people he talks to seem to be trying to get him to stop investigating, which of course only makes Wolfe all the more stubborn. The devilish question he has to answer is, How do you solve a murder when everyone connected to the victim swears it's a suicide?