When the American plutocrat Sigsbee Manderson is found dead on his estates, Philip Trent is asked by the editor of the Record to investigate the mysterious case. What caused Manderson to rise in the middle of the night and leave the house without properly dressing and without his false teeth? Who did he meet and why? Who was the murderer? Marlowe, his personal secretary? Brunner, his business assistant? Or his beautiful wife? Will Trent be able to solve the mystery? Or will this be Trent's Last Case?