Additional Study Information: This study is being done to answer the following question: Can we lower the chance of your cancer returning by adding the drug olaparib to the usual radiation therapy for your cancer? We are doing this study because we want to find out if this approach is better or worse than the usual approach for your inflammatory breast cancer. The usual approach is defined as care most people get for inflammatory breast cancer when they have already received chemotherapy and had surgery to remove the cancer. If you decide to take part in this study, you will get either the usual radiation therapy plus the study drug olaparib (Group 1) for up to 6 weeks, or you will get the usual radiation therapy alone (Group 2) for up to 6 weeks. After you finish the study treatment, your doctor will continue to follow your condition until 8 years after you started the study and watch you for side effects. You will be seen about 5 weeks after you finish the study treatment, then about every 3 months for up to 3 years after you started taking part in this study or until your disease comes back. Then, from 3 years after you started taking part in this study or from the time that your disease comes back, you will be seen about every 6 months until up to 8 years after you started taking part in this study. Your doctor will run blood tests and check your disease status at these visits.