Louis (Dennis Price)'s mother was born into the noble Astene family, but she eloped with an Italian singer and was rejected by the family until her death. As an adult, Louis deeply remembered the faces of his noble relatives who refused to bury his mother in the family cemetery, and experienced his beloved girl Sibella (Joan Greenwood) refusing his proposal because of his poverty, so he set out to launch his revenge plan. He murdered male relatives who had the right to inherit the title one by one, aiming to get the duke's title. After killing became more and more handy, he even refused to let go of the elderly, women and children. Anyway, he could always create various coincidences, and no one ever suspected him. But while executing his revenge plan, he also fell into emotional troubles-Sibella, who had married, was still connected with him, and Edith (Valerie Hobson), a beautiful widow in the family, fell in love with him and was willing to be engaged to him. When Louis proudly inherited the title and held a wedding, his crimes seemed to be exposed...