Serhiy Nosach knew that Russian soldiers hunting out implacable opponents of their occupation of southern Ukraine would one day come for him. He taught Ukrainian history and “defence of Ukraine” classes at a school in Beryslav, a town on the Dnipro river in Kherson region that Russians seized soon after their invasion last February, and many of his former pupils had joined the military and police force. Nosach was blindfolded and taken from his home on August 5th, joining what Ukraine says are thousands of its civilians who are now held – often incommunicado and subject to torture – in...