Vina Nadjibulla (Photograph by Eric Putz) Michael Kovrig walks at least 7,000 steps a day in laps of his cell, along with doing push-ups and planks and practising yoga and meditation. Among his few possessions are a grey uniform, a bar of soap, two Hello Kitty washcloths and a small set of matching plastic cups and bowls. He can read a limited number of books his family sends, but he is allotted only a few hours each month with a pen and paper to write letters and process his thoughts. The world beyond the prison gates ground to a halt over the last year because of the pandemic, but Kovrig,...