Wealthy Mr. Kennedy shoots his secretary, Channing, during a parlor game, but it turns out the gun was loaded with real bullets. Luckily, criminologist Phillip Montrose is on hand to help the police. When Kennedy quickly ends up dead as well, the police think it's a tidy murder-suicide, but the family lawyer knows of a letter that voiced Kennedy's suspicions about someone who was out to get him. Soon, the cops are on the trail of a ruthless and clever killer who is one step ahead of even Montrose.
Infamous burglar "The Bat" commits a daring jewelry theft despite heavy police presence. Soon after, a bank theft occurs, which may be the work of the criminal as well. Meanwhile, Cornelia Van Gorder has various people arrive at her old mansion, including her niece, Dale, a bank employee, and police detective Anderson. When guests start turning up dead, Cornelia begins to suspect that The Bat may be lurking around the estate.
Margaret Holt and her brother Victor set out to smash a narcotics ring responsible for their father's death. Young reporter John Howell and eccentric mystery writer Winthrop Clavering help unravel the truth about the murder.
When actress Diana Baring is found in a daze beside her colleague’s murdered body, all evidence points to her guilt. During the trial, juror Sir John Menier doubts the verdict, but yields to pressure. Haunted by remorse, he launches his own investigation.
After a vaudeville performer is murdered backstage, framed-up evidence lead the police to arrest a troupe member. At his trial, Hermann, a Scandinavian clown known as Beppo, is the lone juror holding out against conviction and pleading for his innocence and acquittal.
Although his murdered friend was by all accounts a scoundrel, Edward Wales is determined to trap his killer by staging a seance using a famous medium. Many of the 13 seance participants had a reason and a means to kill, and one of them uses the cover of darkness to kill again. When someone close to the medium is suspected she turns detective, in the hope of uncovering the true murderer.
Sir George hires Hillary Gatt to find out more about Eric who wants to marry Lois. Gatt is murdered and the couple, married, run off to India. Old friend John Beetham sympathizes with the bride who sees that her hubby is a liar and drunk.
Mrs. Ramsey sent Jean Oliver to prison on a false charge. To get even, Jean (disguised as Madame Mystera) plans to kidnap her daughter and turn her into a thief. Love entanglements with a gangster known as "The Fox" and newspaperman Grant complicate her plans.
A beautiful showgirl, name "the Canary" is a scheming nightclub singer. Blackmailing is her game and with that she ends up dead. But who killed "the Canary". All the suspects knew and were used by her and everyone had a motive to see her dead. The only witness to the crime has also been 'rubbed out'. Only one man, the keen, fascinating, debonair detective Philo Vance, would be able to figure out who is the killer.
Rich old Cyrus West's relatives are waiting for him to die so they can inherit. But he stipulates that his will be read 20 years after his death. On the appointed day his expectant heirs arrive at his brooding mansion. The will is read and it turns out that Annabelle West, the only heir with his name left, inherits, if she is deemed sane. If she isn't, the money and some diamonds go to someone else, whose name is in a sealed envelope. Before he can reveal the identity of her successor to Annabelle, Mr. Crosby, the lawyer, disappears. The first in a series of mysterious events, some of which point to Annabelle in fact being unstable.
London. A mysterious serial killer brutally murders young blond women by stalking them in the night fog. One foggy, sinister night, a young man who claims his name is Jonathan Drew arrives at the guest house run by the Bunting family and rents a room.
After a man kills two members of his Yukon gold prospecting team, the other two surviving members struggle to keep him subdued for the next several months until they can turn him over to the law.