‘Oh, quite frequently. The centuries we used to call the Dark Ages were dangerous times in which to live. Vikings were claiming more and more territory, and warring princes and kings across Britain were constantly doing battle with one another.’

Tilda reaches forward and touches the map where the small area of green upon the lake signifies the crannog. ‘Strange. To even think about living on the lake like that. Weren’t they worried the thing might sink? It had to support houses, all those people, horses…’

‘Evidently any such fears would have been unfounded. The island still stands a thousand years after it ceased being inhabited. No, the greatest danger to the people of the lake came not from their surroundings, but from man’s inability to live in peace with his neighbors. An unchanging fact, sadly.’

They are interrupted by a sudden movement by the fire. Thistle scrambles to her feet and lets out a low growl as a man walks into the room. Tilda recognizes him at once as the diver she encountered a few days earlier. He is tall and lean, his unruly black hair more ringlets than curls, and his skin the color of warm honey. Now that she can see him properly, without his wet suit hood or mask, she is struck by how unusual he is. His dark complexion and bright green eyes suggest a mixed ethnicity, as does the glossy blackness of his hair oddly matched with his angular European features. Realizing she is staring at him, and conscious of the irony of this, she experiences a niggling shame about what she did to his boat.

‘Ah,’ the professor beams, ‘Dylan, come in, come in.’

‘I will if your visitor promises not to bite me,’ he says, nodding at the dog.

Tilda slips out from behind the desk and goes to Thistle, putting a hand on the animal’s head. ‘She won’t hurt you,’ she says. ‘She was just startled. You woke her up.’

Professor Williams laughs. ‘And you know what they say about letting sleeping dogs lie! Tilda, this is my nephew, Dylan.’

‘We’ve met,’ Dylan says with a grin. ‘Though I remember you as…’ He pauses, then says, ‘wetter.’

‘How’s your boat?’ Tilda asks, struggling to meet his gaze. She is annoyed to find she feels self-conscious; aware of being in her unflattering running clothes and mismatched spotty socks, with her hair flattened from her hat. Thistle has stopped growling, but keeps her eyes fixed on the newcomer.

That’s two of us he’s making nervous. Ridiculous. We should get out more.

‘There’s tea in the pot,’ says the professor. ‘Tilda has moved in to Ty Gwyn. Marvelous views from up there. My nephew is on a rare visit home, not on my account, it has to be said.’

‘Now Uncle Illtyd will give you a hard-luck story about how he never sees me.’