Philo Vance's Secret Mission

In New York City, renowned detective Philo Vance and his assistant, Ernie Clark, meet with Argo Publications owner Martin Jamison. To the surprise of his partner, Paul Morgan, and Morgan's secretary, Mrs. Phillips, Jamison, whose firm publishes pulp horror stories, asks Philo to write a mystery novel for him. In the presence of two of his best writers, Carl Wilson and Louise Roberts, Jamison announces that the novel will be based on the real-life, unsolved murder of his partner, Haddon Phillips, who was killed seven years before. Jamison then declares that he has finally deduced who the killer is, causing Mrs. Phillips, Haddon's widow, to faint. When Jamison invites Philo to his country estate the next morning to hear details about the murder, Mona Bannister, Jamison's attractive secretary, offers to drive the detective there. Philo and Mona also have a date for that night, but while they are sharing a romantic moment at her apartment, she receives a frantic call from Jamison. The couple rushes to Jamison's estate, arriving in time to hear gunshots and Jamison's cries of distress. They are unable to find Jamison, however, and cannot catch the man who is fleeing. After notifying the local sheriff about the matter, Philo and Mona head home, but are soon stopped by a motorcycle officer, who discovers Jamison's body in their trunk. Philo and Mona are cleared by the sheriff, who accompanies Philo to Argo the next morning. Philo and the sheriff question their suspects--Morgan, Mrs. Phillips, Louise, Curt and Joe, Argo's cover photographer--and reveal that the murder weapon was stolen from the photographic studio. In the heat of the moment, Mrs. Phillips accuses Morgan of killing her husband for his $50,000 company insurance policy, which will finally be paid out the following week. Later, Philo instructs Mona to tell Mrs. Phillips that he will be coming by to talk to her that night and then questions a representative of Argo's insurance company about Phillips' policy. The representative reveals that, in addition to his company policy, Phillips had a $100,000 personal policy, which Mrs. Phillips took out just before his murder. The representative also states that shortly before his murder, Phillips had been accused by Jamison of embezzlement and that Argo's lawyer, Thaddeus Carter, was present at Phillips' murder scene. Philo then learns that Carl was angry at Phillips because of a failed real estate venture and orders Ernie to tail the writer. That night, as Philo and Mona are driving to Mrs. Phillips' house, they are shot at by a man in another car and are forced to flee into some woods. There Philo fights off the armed man, who escapes to his car and drives away. Concerned for Mrs. Phillips' safety, Philo and Mona rush to her house, but discover that she is readying to leave for South America with her fiancé, Carter. The next morning, Philo asks the sheriff to call all the suspects to an afternoon meeting at Argo. There Philo announces that Mona and her "boyfriend" killed Jamison, but later reveals to a shocked Mona that he implicated her in order to trap the real killer. After Philo predicts that both murders will be solved by the next morning, he, Mona, Ernie and the sheriff surprise Mrs. Phillips and Carter on their cruise ship just before it is to sail. When Philo declares that Carter must be protected, a nervous Mrs. Phillips insists that she and Carter immediately marry. Just then, a gun-wielding Phillips bursts into the stateroom and is apprehended by the sheriff. Philo explains that, with his wife's help, Phillips faked his own murder to avoid prosecution on embezzlement charges and to collect on his life insurance. When Jamison deduced his scheme, Philo states, Phillips killed him, and Mrs. Phillips rushed to marry Carter at sea. Phillips planned to kill Carter on the ship and then assume his identity in South America. The case solved, Mona tries to convince Philo to marry her, but the confirmed bachelor proves to be a very tough case.