‘Ben, what was that stuff you were saying earlier about the circles of hell?’

‘The ninth circle, to be exact.’

‘Isn’t that what Aidan Merritt was rambling about when he called his wife, just before he was killed?’

‘That’s right. Everyone thought it was to do with the fires on the moor. He must have gone right through the smoke to get to the Light House. But there was something Betty Wheatcroft said to me. She pointed out that it was from Dante’s Inferno.’

‘The old biddy’s not as daft as she looks, then?’

‘No, not at all. I don’t know where she gets her information from, but she knows more than she lets on. She’s stubborn, though. Likes to play her own game. There was some detail she would have given me, if I’d asked the right question. I just didn’t know what the question was.’

‘Perhaps she just needs you to show a bit more interest,’ said Villiers.

Cooper stopped by his car. ‘You think so, Carol?’

‘A lonely old lady, isn’t she? I bet she really took to you, and enjoyed having a chat. So instead of telling you everything, she thought of a way of making you come back to see her again.’

He stared at her, astonished by the clarity of the insight. To him, it seemed a devious way of thinking. But in Mrs Wheatcroft’s case, it rang so true.

They got in the car, and Cooper started the engine. He had Betty Wheatcroft’s phone number in his notebook, but he had to wait until they were well down the road and on to Batham Gate before he could get a signal. The old lady’s phone rang and rang, without even an answering machine or call minder cutting in.

‘No answer,’ he said. ‘She must be out.’

‘Where does Mrs Wheatcroft go now?’ asked Villiers, as they approached the sharp bend on Batham Gate.

‘What do you mean?’

‘What pub does she go to? She can’t have stopped going for a drink just because the Light House closed.’

‘Well, as I said before, she went to the Light House for the company, because she knew people there.’

‘Okay, so where did the people that she knew start going when it closed?’

‘I don’t know.’ But then Cooper stopped, and corrected himself. ‘Yes I do. Ian Gullick told me. He said they drink at the Badger, near Bradwell.’

‘Could Mrs Wheatcroft get there easily?’

‘It’s on the same bus route as the Light House, and a good bit closer to where she lives.’

‘It’s worth a try, if we have time.’

‘We’re almost there,’ said Cooper. ‘Another two minutes, and we’ll pass it.’

Betty Wheatcroft had found a corner for herself in the bar of the Badger, and was sitting with her glass and her plastic carrier bag, trying to ignore the loud background music and the beeps and buzzes of the fruit machines. This was a different kind of place, not what she’d been used to at the Light House.

Cooper saw her as soon as he came through the door. He noticed that her glass was almost empty, so he went first to the bar and bought her a half-pint of Guinness. She smiled when she spotted him, losing for a moment that slightly mad, desperate look. There was no surprise on her face. She gave the impression that she’d been expecting him, that he could even be slightly late. She might be putting a black mark next to his name in an imaginary attendance register.

‘How nice,’ she said. ‘And what a good idea not to come to my house. People would start to talk.’

‘I’m very glad I caught you, Mrs Wheatcroft,’ said Cooper. ‘There’s something I need to ask you.’

She looked anxiously round the bar, then buried her face in her glass. She seemed somehow reassured by the slosh of the black liquid.

‘What is it?’

‘Last time I visited you, I mentioned the ninth circle of hell, and you said it was—’

‘The Inferno. It’s by the great Italian poet Dante Alighieri. The first part of his Divine Comedy. All about the medieval concept of hell. Lovely, isn’t it?’

Cooper wasn’t quite sure what she was referring to. At first he thought it might be the Guinness, or the music now playing in the background. Lynyrd Skynyrd’s ‘Free Bird’, if he wasn’t mistaken. Not really Mrs Wheatcroft’s cup of tea, he imagined. So she must be referring to Dante’s vision of hell.

‘There’s something particular about the ninth circle,’ he said.

‘Judas, Brutus and Cassius.’

‘Sorry?’

‘Judas, Brutus and Cassius,’ she repeated more slowly, as if remembering that he was one of her slower pupils. ‘The ninth circle of hell. It’s all about treachery.’

‘Yes, that’s what I was thinking.’

She took another gulp of her drink. ‘In Dante’s Inferno, each of the nine circles is reserved for a particular sin. They get more and more wicked as they move towards the middle. The ninth circle was reserved for the very worst sinners – the traitors. Judas, who betrayed Jesus. And Brutus and Cassius who stabbed Julius Caesar in the back. Do you remember this at all?’

Cooper nodded, hoping not to have to reveal the true depths of his ignorance.

‘Is that what Aidan Merritt was talking about?’

‘Yes, I think it must have been.’

She seemed to lose track of the conversation, gazing across the bar at no one in particular, then poking in her carrier bag as if she’d lost something.

Cooper tried to curb his impatience. He had faith in Carol’s assessment. He had to let Betty Wheatcroft play her own game, at her own pace, if he wanted to get everything she knew out of her.

‘The traitors,’ he said slowly.

‘Oh.’ She licked her lips thoughtfully. ‘Thank you. Well, in the ninth circle there were three different grades of treachery. Betrayal of family, betrayal of community, betrayal of … guests.’

‘Guests?’

‘Yes. A breach of the unwritten laws. The ancient code of hospitality.’

Cooper sat back in his chair, and looked at the old lady, with her wild hair and her plastic carrier bag. Many people would pass her by without a second glance.

‘Mrs Wheatcroft, where do you get your information from?’ he asked.

‘Oh, I know it all,’ she said.

‘People tell you what they’re doing?’

‘No, not them,’ she said, with a flash of contempt. ‘Nobody ever spoke to me at the Light House, except for Aidan. As far as they were concerned, I was just the daft old trout in the corner. It’s the same here at the Badger. And because they don’t talk to me, they think I don’t hear anything. I suppose they reckon I must be deaf. But I do hear. I hear everything.’

‘And what did you hear in this case, Mrs Wheatcroft?’

She put a finger to the side of her nose. ‘They thought Aidan was going to betray them. But he was a decent man. Weak, but decent.’

Betty Wheatcroft suddenly looked very sad. Cooper knew she’d liked Aidan Merritt, and he’d wondered how long she could hold that back and pretend she wasn’t too disturbed by his death. Her charade of secrecy was just part of the game. Underneath, she was a frightened woman.

‘Who are they? Who thought he was going to betray them?’ he asked.

‘I can’t tell you,’ she said.

‘Mrs Wheatcroft …’

‘No,’ she snapped firmly. ‘Be told.’

He shut up immediately, hearing the exact same words and tone of voice that his grandmother had used to him when he was a child, pestering for an ice cream.

In another moment, she’d changed the subject back to safer ground. The past, the theoretical – so much less dangerous than the real, physical present. He wondered if she was scared by a genuine threat from some specific source, or whether she feared to make herself one more soul who was guilty of the sin of betrayal.

‘Do you happen to have a copy of this book, Mrs Wheatcroft?’ asked Cooper.

‘The Inferno? No, why would I? Look it up, if you want.’

‘I’ll google it,’ he said.

‘Yes, you do that.’

She laughed then. It wasn’t quite a cackle, but a chortle with an edge of unhealthy glee. Cooper thought perhaps he shouldn’t have bought her that extra Guinness.