The small town of Sodbury Cross is shaken by a series of mysterious poisonings. The murderer acts with deadly certainty, and suspicion falls each time on Marjorie Wills, a young heiress to a vast fortune. It is difficult to prove her guilt, but why is she always at the scene of the crime? And isn’t it strange that she really does have reasons to commit all these murders? Young Inspector Eliot, who is in love with Marjorie, understands that one more step and she will have to answer for what she did not do. Then he turns to Dr. Fell — the only one capable of finding the real poisoner…