White Murder - MR David Wishart

'Uh...Dad?' Young Lucius's face was chalk white. 'Dad, I think he's dead.' It took a moment to register. Then Renatius dropped the towel and was through the door in five seconds flat, and the rest of the wineshop, including me, were about two seconds behind him. When Pegasus, racing mega-star and lead driver of the Whites faction, is found stabbed to death in the alleyway beside Renatius's wineshop, Marcus Corvinus is already on site. The local District Watch - crooked to a man - claim that the killer's motive was simple theft, but Corvinus knows it wasn't. Tracking the murderer down, with the often-unwilling help of his wife Perilla, takes him deep into the murky world of Roman chariot-racing with all its secrets, skulduggeries and scams; and his task is not made any easier by the fact that in the process he has a lovesick major-domo, an invisible dagger and Mount Etna to contend with. The seventh book in the Marcus Corvinus series.