Each year, 12 million underaged girls are forced into marriage - a crisis that at the current rate will take over 300 years to fix, says the UN. Now, three of the world's most high-profile humanitarians have vowed to tackle the issue together. In a BBC 100 Women exclusive, Michelle Obama, Amal Clooney and Melinda French Gates talk to BBC Gender and Identity Correspondent Megha Mohan about the work they do to combat child marriage and amplify the efforts of grassroots organisations. Directed by Yousef Eldin. Show less