For the last two years, Pu Wenqing, 85, has spent most of her time writing articles about her son, Huang Qi, a long-time dissident who has been in prison for more than two years awaiting trial. She posts updates about Huang, the founder of China’s first known human rights monitoring website, on Wechat and in October she recorded a video, pleading for help, and posted it on YouTube. Now, Granny Pu, as she is known to her friends, has disappeared and is likely under house arrest or in a black jail, according to friends and human rights advocates.