'Or murder,' said Hugo Tilling.

'Find yourself a nice simple case of murder.'

As if in obedience to some secret code, they began getting up, piling their books together, brushing the grass cuttings from their clothes. Cordelia followed them through the courts and out of college. Still in a silent group they made their way to a white Renault parked in the forecourt.

Cordelia came up to them and spoke directly to Isabelle.

'Did you enjoy the Pinter? Weren't you frightened by that dreadful last scene when Wyatt Gillman is gunned down by the natives?'

It was so easy that Cordelia almost despised herself. The immense violet eyes grew puzzled.

'Oh, no! I did not care about it, I was not frightened. I was with Hugo and the others, you see.'

Cordelia turned to Hugo Tilling.

'Your friend doesn't seem to know the difference between Pinter and Osborne.'

Hugo was settling himself into the driving seat of the car. He twisted round to open the back door for Sophie and Davie. He said calmly:

'My friend, as you choose to call her, is living in Cambridge, inadequately chaperoned I'm happy to say, for the purpose of learning English. So far her progress has been erratic and in some respects disappointing. One can never be certain how much my friend has understood.'

The engine purred into life. The car began to move. It was then that Sophie Tilling thrust her head out of the window and said impulsively:

'I don't mind talking about Mark if you think it will help. It won't, but you can come round to my house this afternoon if you like – 57 Norwich Street. Don't be late; Davie and I are going on the river. You can come too if you feel like it.'

The car accelerated. Cordelia watched it out of sight. Hugo raised his hand in ironic farewell but not one of them turned a head.

Cordelia muttered the address to herself until it was safely written down: 57 Norwich Street. Was that the address where Sophie lodged, a hostel perhaps, or did her family live in Cambridge? Well, she would find out soon enough. When ought she to arrive? Too early would look over eager; too late and they might have set out for the river. Whatever motive prompted Sophie Tilling to issue that belated invitation, she mustn't lose touch with them now.

They had some guilty knowledge; that had been obvious. Why else had they reacted so strongly to her arrival? They wanted the facts of Mark Callender's death to be left undisturbed. They would try to persuade, cajole, even to shame her into abandoning the case. Would they, she wondered, also threaten? But why? The most likely theory was that they were shielding someone. But again, why? Murder wasn't a matter of climbing late into college, a venial infringement of rules which a friend would automatically condone and conceal. Mark Callender had been their friend. Someone whom he knew and trusted had pulled a strap tight round his neck, had watched and listened to his agonized choking, had strung his body on a hook like the carcase of an animal. How could one reconcile that appalling knowledge with Davie Stevens's slightly amused and rueful glance at Sophie, with Hugo's cynical calm, with Sophie's friendly and interested eyes? If they were conspirators, then they were monsters. And Isabelle? If they were shielding anyone, it was most likely to be her. But Isabelle de Lasterie couldn't have murdered Mark. Cordelia remembered those frail sloping shoulders, those ineffective hands almost transparent in the sun, the long nails painted like elegant pink talons. If Isabelle were guilty, she hadn't acted alone. Only a tall and very strong woman could have heaved that inert body on to the chair and up to the hook.

Norwich Street was a one-way thoroughfare and, initially, Cordelia approached it from the wrong direction. It took her some time to find her way back to Hills Road, past the Roman Catholic church and down the fourth turning to the right. The street was terraced with small brick houses, obviously early Victorian. Equally obviously, the road was on its way up. Most of the houses looked well cared for; the paint on the identical front doors was fresh and bright; lined curtains had replaced the draped lace at the single ground-floor windows and the bases of the walls were scarred where a damp course had been installed. Number fifty-seven had a black front door with the house number painted in white behind the glass panel above. Cordelia was relieved to see that there was space to park the Mini. There was no sign of the Renault among the almost continuous row of old cars and battered bicycles which lined the edge of the pavement.

The front door was wide open. Cordelia pressed the bell and stepped tentatively into a narrow white hall. The exterior of the house was immediately familiar to her. From her sixth birthday she had lived for two years in just such a Victorian terraced cottage with Mrs Gibson on the outskirts of Romford. She recognized the steep and narrow staircase immediately ahead, the door on the right leading to the front parlour, the second door set aslant which led to the back parlour and through it to the kitchen and yard. She knew that there would be cupboards and a curved alcove on each side of the fireplace: she knew where to find the door under the stairs. Memory was so sharp that it imposed on this clean, sun-scented interior the strong odour of unwashed napkins, cabbage and grease which had permeated the Romford house. She could almost hear the children's voices calling her outlandish name across the rookery of the primary school, playground across the road, stamping the asphalt with the ubiquitous Wellington boots which they wore in all seasons, flailing their thin jerseyed arms: 'Cor, Cor, Cor!'

The furthest door was ajar and she could glimpse a room painted bright yellow and spilling over with sunlight. Sophie's head appeared.

'Oh, it's you! Come in. Davie has gone to collect some books from college and to buy food for the picnic. Would you like tea now or shall we wait? I'm just finishing the ironing.'

'I'd rather wait, thank you.'

Cordelia sat down and watched while Sophie wound the flex around the iron and folded the cloth. She glanced around the room. It was welcoming and attractive, furnished in no particular style or period, a cosy hotchpotch of the cheap and the valuable, unpretentious and pleasing. There was a sturdy oak table against the wall; four rather ugly dining chairs; a Windsor chair with a plump yellow cushion; an elegant Victorian sofa covered with brown velvet and set under the window; three good Staffordshire figures on the mantelshelf above the hooded wrought-iron grate. One of the walls was almost covered with a notice-board in dark cork which displayed posters, cards, aides-memoire, and pictures cut from magazines. Two, Cordelia saw, were beautifully photographed and attractive nudes.

Outside the yellow-curtained window the small walled garden was a riot of greenery. An immense and multi-flowered hollyhock burgeoned against a tatty looking trellis; there were roses planted in Ali Baba jars and a row of pots of bright-red geraniums lined the top of the wall. Cordelia said:

'I like this house. Is it yours?'

'Yes, I own it. Our grandmother died two years ago ancT left Hugo and me a small legacy. I used mine for the down payment on this house and got a local authority grant towards the cost of conversion. Hugo spent all of his laying down wine. He was ensuring a happy middle age; I was ensuring a happy present. I suppose that's the difference between us.'

She folded the ironing cloth on the end of the table and stowed it away in one of the cupboards. Sitting opposite to Cordelia, she asked abruptly:

'Do you like my brother?'

'Not very much. I thought he was rather rude to me.' 'He didn't mean to be.'

'I think that's rather worse. Rudeness should always be intentional, otherwise it's insensitivity.'