A Corruption of Blood is the third instalment of the brilliant Dr Will Raven and Sarah Fisher thrillers set in Edinburgh in the 1850s. The plot swirls around a medical mystery, the details of which cannot be repeated here. Instead of a spoiler, what can be said is that this is the best so far of the three Ambrose Parry novels. Its background is the University of Edinburgh, medical experiments and the world of Sarah’s landlord, Dr James Simpson, a pioneer in the use of chloroform. The fog, the stench and the menace of Edinburgh’s Old Town reek off the pages and are marshalled into a riveting story. Ambrose Parry is the nom de plume used by the gifted Chris Brookmyre and his brilliant wife, Marisa Haetzman.