S1, E3: There are few parts of the world that haven't been touched by slavery. Over the last thousand years, slave trade networks have stretched across the globe, from Venice to Tanzania. In this episode we bring the realities of the global slave trade to human scale, following the sister of British prime minister Boris Johnson to Istanbul, where she makes a startling discovery about her great, great grandmother. Meanwhile, conductor Karen Gibson travels to Lisbon to explore the exceptional story of 18th century African musician Joseph Emidy.