Instead of thinking to join directly in a firm without any work experience and no masters in it, will suggest you to start with internship in it. Check websites like Internshala nd Letsintern which can help you with firms looking for candidates like you. Also you can approach directly by sending mails or calling them if they are open to take you up. So basically an aggressive approach in companies you are interested to join can help you with it. Top companies are BCG and Bains. There are others. Start your search!