The third Elizabeth Barnabus book set in the gas-lit Empire, following on from The Bullet Catcher's Daughter and Unseemly Science. Elizabeth is on the run from the authorities as both halves of Britain – independent and suspicious of each other – prepare to sign an extradition treaty that could send Elizabeth and all the Kingdom refugees back home against their will. If that happens the slimy Duke of Northampton will be waiting to snatch her into sexual slavery. Elizabeth takes to the canals in order to become invisible to the law, but eventually takes matters into her own hands in a dangerous, last-ditch attempt to be free. We meet some old friends from previous books. There's a slow burn romance with Patent Office agent John Farthing, a daring heist, and a satisfying resolution. I've thoroughly enjoyed the whole trilogy and I see that Elizabeth is back in The Queen of All Crows, book 1 of a new trilogy. Excellent!