Their friendship began on July 17, 2014, with whispered secrets shared through the vent in the wall that separated their cells. Jessica Burlew remembers the exact date because she’d turned 17 the day before, the same day that Mariam Abdullah, then 16 and about to be charged as an adult with armed robbery, had been brought to Estrella Jail in Phoenix, Arizona. When Abdullah arrived, shackled and belly chained, in the closed custody unit, where girls deemed incorrigible were held in their cells for 23 hours a day, Burlew had been there for about six months. In that time, Burlew said she hadn’t had any contact with other teens and so was glad to hear Abdullah’s voice. “I very much did consider Mariam a birthday present,” Burlew, now 22, wrote from Perryville Prison in Goodyear, Arizona, where she is serving a 10-year sentence.  Over the months they were held in isolation, speaking through that vent, Burlew and Abdullah shared the things that teenagers do. Abdullah’s favorite color was red. She wanted to be a firefighter. Her favorite musical artist was Drake. For the next two years, Abdullah spent much of her time separated from others, both to discipline her for what was classifi...