London, 1924. When shy academic Lao She meets larger-than-life Judge Dee Ren Jie, his quiet life abruptly turns from books and lectures to daring chases and narrow escapes. Dee has come to London to investigate the murder of a man he'd known during World War I when serving with the Chinese Labour Corps. No sooner has Dee interviewed the grieving widow than another dead body turns up. Then another. All stabbed to death with a butterfly sword. Will Dee and Lao be able to connect the threads of the murders - or are they next in line as victims?