The Power of the Holy Rosary
There was once a woman who gave herself to the devil and even signed the contract with her blood. But she deeply regret it soon afterwards and had a great desire to make reparation for what she has done. So she asked a confessor who advised her to see Father Henry - a Dominican and director of the Confraternity of the Holy Rosary. So she went to and asked to see him, but instead of Fr Henry, she met a devil disguised as a friar who condemned her mercilessly and told her there is no hope that she will receive God's grace again and to retract what she had signed. Although she was terribly upset but she still has hope in God's Mercy and ask to see Fr Henry again, but she met the devil again and received the same treatment a second time. Yet she went back there a third time and by God's Providence she finally found Fr Henry in person. The Priest was very kind to her and advised her to throw herself on God's Mercy and make a good confession. He then enrolled her into the Confraternity and told her to say the Holy Rosary often. One day, while Fr Henry was offering Mass for her, Our Blessed Lady forced the devil to give Her back the contract the woman has signed. Thus, through the authority of Our Lady and this woman's devotion to the Holy Rosary, she was delivered from the chains of the devil.
(Reference: The Secret of the Rosary, by St Louis Mary Grignion de Montfort)