Depleted and exhausted, she blinked away more tears and wiped her wet face with the heels of her hands. Muffled voices rose from the kitchen below her room. Her mother, she was sure, would be advising Matthew to leave her alone for a while. Robin hoped that he would listen. She felt as though she would like to sleep through the rest of the weekend.

An hour later she was still lying on the double bed, staring drowsily out of the window at the top of the lime tree in the garden, when Matthew knocked and entered with a mug of tea.

“Your mum thought you could use this.”

“Thanks,” said Robin.

“We’re all going to watch the National together. Mart’s put a big bet on Ballabriggs.”

No mention of her distress or of Martin’s crass comments; Matthew’s manner implied that she had somehow embarrassed herself and he was offering her a way out. She knew at once that he had no conception of what the sight and feel of that woman’s leg had stirred up in her. No, he was simply annoyed that Strike, whom none of the Ellacotts had ever met, was once again taking up space in weekend conversation. It was Sarah Shadlock at the rugby all over again.

“I don’t like watching horses break their necks,” said Robin. “Anyway, I’ve got some work to do.”

He stood looking down at her, then walked out, closing the door with a little too much force, so that it jumped open again behind him.

Robin sat up, smoothed her hair, took a deep breath and then went to fetch her laptop case from on top of the dressing table. She had felt guilty bringing it along on their trip home, guilty for hoping that she might find time for what she was privately calling her lines of inquiry. Matthew’s air of generous forgiveness had put paid to that. Let him watch the National. She had better things to do.

Returning to the bed, she made a pile of pillows behind her, opened the laptop and navigated to certain bookmarked webpages that she had talked to nobody about, not even Strike, who would no doubt think she was wasting her time.

She had already spent several hours pursuing two separate but related lines of inquiry suggested by the letters that she had insisted Strike should take to Wardle: the communication from the young woman who wished to remove her own leg, and the missive from the person who wished to do things to Strike’s stump that had made Robin feel faintly queasy.

Robin had always been fascinated by the workings of the human mind. Her university career, though cut short, had been dedicated to the study of psychology. The young woman who had written to Strike seemed to be suffering from body integrity identity disorder, or BIID: the irrational desire for the removal of a healthy body part.

Having read several scientific papers online, Robin now knew that sufferers of BIID were rare and that the precise cause of their condition was unknown. Visits to support sites had already shown her how much people seemed to dislike sufferers of the condition. Angry comments peppered the message boards, accusing BIID sufferers of coveting a status that others had had thrust upon them by bad luck and illness, of wanting to court attention in a grotesque and offensive manner. Equally angry retorts followed the attacks: did the writer really think the sufferer wanted to have BIID? Did they not understand how difficult it was to be transabled—wanting, needing, to be paralyzed or amputated? Robin wondered what Strike would think of the BIID sufferers’ stories, were he to read them. She suspected that his reaction would not be sympathetic.