Petronius shook his head. ‘The twins arrive in Rome. Anacrites quickly grasps his error: he will never shake them off. They start whining about conditions on the marshes. Their background is a reproach, their presence in Rome an embarrassment. They threaten the spy’s ambitions.’

‘He wants out?’ asked Quintus. ‘But they refuse to go.’

‘Anacrites’ unpredictability increases due to his head wound,’ Helena said. ‘He becomes vulnerable at work, with his position threatened by Laeta and even by Momus. At some ghastly point he learns the kind of crimes Nobilis and the others have committed. By then he cannot escape.’

‘And so we come to the Modestus murder.’ I screwed my thumbs into my belt and took charge of the final argument. ‘Everything went wrong with the fence dispute. Up to that point, I’d say Nobilis probably carried out all his killings in the area around Antium—the bodies Silvius has found. Nobilis and various brothers abducted people for years, usually travellers, often couples. Those cases were concealed, but he lost it with Modestus. By tailing Modestus to Rome, for once Nobilis left a trail. Nobilis—presumably with Pius or Virtus—killed Modestus on the Via Appia. They spent several days at the crime site, desecrating the body, then Nobilis went home. Primilla came looking for her husband, so he killed her too, with her overseer, Macer. That meant her nephew alerted the authorities and a posse arrived to shake down the Claudii. From then on, we can assume pressure was put upon Anacrites to protect them. That may well have been when one of them told him about the murders. It made him more insecure and dangerous. Crucially, he inherited the same manipulative traits as the rest of them—a situation which they may not have foreseen. He turned on them.’

‘He may have been appalled by their crimes,’ Helena said, always fair.

‘He was certainly furious about how it threatened him personally! Perella was sent after Nobilis, but Nobilis got away. Anacrites tried to remove Nobilis from the scene, taking him to Istria. Whose idea that was we can never know. Perhaps they really found their grandmother. One way or another, Nobilis refused to play; he would not stay in exile. Idiotically, he sailed back with Anacrites—who then must have been as close to hysteria as he ever gets.’

‘Not him!’ Albia scoffed. ‘He thinks himself invincible. In his eyes, everything that happens is manipulated by him. He believes he is a genius. When I was in his house he said, “Falco can’t touch me; I run rings around him”. He had been drinking, but he meant it.’

With a glance at Petronius, I said slowly, ‘He may in fact have been more clever than we think. What Anacrites achieved may not have been entirely crude. The way he grabbed the Modestus case and warned off Petronius and me seems plain stupid. Some of his actions—house searches, annoying the Vestals—seem worse.’