But I’d enjoyed the orderliness of digging, knowing how to use the pick, shovel, trowel, brush, sieve. After a day’s hard work, my hair sweaty and flattened beneath a hard hat, my shoulders would ache. And I’d be exhausted enough to believe, like Marco, that uncovering the truth required nothing more than having the right equipment and knowing how to use it.

Marco’s email deserved a reply. I didn’t know how to begin. I had to tell him about Caleb. In the body of his email, Marco described a Roman dining room with an ivory ceiling that moved aside, releasing a rain of perfumed petals. The floor was round, and revolved constantly, day and night like the Heavens, he wrote. The ancients were fascinated by the mechanical. Hephaestus, Greek god of blacksmiths, built robot-like automatons of metal to work for him – creatures like Caleb attached to truth-detecting wires. That was Marco’s world, while I was here, living the choice I made when I left him for Stephen.

Relationships are complicated. Stephen had been somewhat jealous of Marco, especially when looking for an excuse to be with Ivy. I saw that now. But in his own eccentric way, Marco was married to his work. I was sure he was occasionally involved with other women, maybe men, but nothing meant as much to him as research. And when one dig finished and he had to move on, he was never sad to do so.

I abandoned my email attempt. The room was brighter – the sun had risen. Caleb still wasn’t home. I couldn’t help reliving his absence during the fire. I’d felt so relieved, finding him on the street, mistakenly believing our crisis was over. I tried his phone again, just in case. Maybe the battery was dead by now. There was nothing to do but wait.

In desperation, I tracked the Caleb who remained accessible, the Caleb who was recorded and secured in my chest of drawers. The Caleb of report cards and school photos, health records and AFL club memberships. His school information was a particular mess, as if searching police officers had suspected evidence of pyromania in his maths results. But one after another, from preschool, until so recently, they showed the same Caleb. There were one or two incidents, notably the marijuana that prompted our move here, but nothing out of the ordinary. Mostly, he was an ideal student, bright, quiet, a sporty high achiever. Not a lout, not a bully, not the antisocial outsider that newspapers described.