still lay with papers scattered around him. On the table were more papers, scribbled over with mysterious-looking diagrams and a box about the size of a gramophone without its horn. The gun, an automatic, belonged to the house. Mrs Lewis’s husband had used it during the war. Hamilton, the butler, couldn’t say if it was usually kept in the study but Mr Lewis might have left it there.
The Inspector drew a deep breath. It seemed like an open and shut case but he was wary of arresting the Professor out of hand. For one thing, he was a professor and therefore a man to treat with respect. But what was really making him pause was Hamilton’s and Eckersley’s assurance that the man was off his head. Inspector Gibson had never had anything to do with loonies before and Hamilton’s confident assertion that the Professor would end up in Broadmoor unsettled him. ‘Mad as a hatter,’ Hamilton had said and he had witnessed the Professor quarrelling with his master. It worried him that Sergeant Atterby so obviously agreed with them.
He squared his shoulders and walked into the library, motioning to Sergeant Atterby to follow him.
The Professor was sitting on a leather sofa beside a younger man who was, presumably, Gerard Carrington. Despite his shabby clothes, the Professor had a real presence, thought Gibson. His eyes were very bright. Unnaturally bright, perhaps. He gave an official cough. ‘Can I have a word with you, sir?’
‘At last!’ Professor Carrington got to his feet. ‘How long will this take?’
‘I’m afraid I can’t say, sir,’ said Gibson. ‘I must ask you to tell me exactly what happened.’
‘I’ve gone through this endlessly,’ said Professor Carrington, clenching his fists in frustration.
‘Dad,’ said Gerard Carrington warningly. ‘This is a police officer. Just answer his questions, will you?’
The Professor sighed in exasperation. ‘Very well.’ He braced his arms against the back of the sofa. ‘If you insist, I’ll go through it again. I had an appointment with Charles Otterbourne to discuss my new recording apparatus. The sound itself is recorded on to magnetic ribbons by means of . . .’
‘What did you actually do, sir?’
‘I invented it.’
Inspector Gibson began to wonder if Professor Carrington was pulling his leg. ‘What did you actually do with regard to Mr Otterbourne, sir?’
Alan Carrington glared at him. ‘Nothing.’
Inspector Gibson coughed once more. ‘You must have done something, sir. Let me just run through the facts of the case as I understand them. You had an appointment with Mr Otterbourne, yes?’
Professor Carrington looked at him wearily. ‘So I’ve said. It was to discuss . . .’
Inspector Gibson held up his hand. ‘Never mind that for the moment, sir. You’d been with Mr Otterbourne in the study, yes?’
‘Yes, of course I was. Great heavens, man, do you usually state the obvious?’
He glanced at his watch. ‘Can you hurry up? I want to catch the train back to London and the best service departs in little over half an hour.’
Inspector Gibson heard Sergeant Atterby’s quick intake of breath. Surely, surely the man must know he was in danger of being arrested for murder? ‘I’m afraid you might have to miss the train, sir,’ he managed to say. He held up his hand to cut off Alan Carrington’s torrent of words. ‘I need to get to the bottom of what occurred this morning. The butler served you and Mr Otterbourne with coffee at approximately quarter past eleven.’ Alan Carrington looked blank. ‘The butler stated he heard you speak very sharply to Mr Otterbourne.’
‘The butler should mind his own business,’ said Carrington distractedly. ‘I might have been a little impatient. It’s a fault of mine, I’m afraid. Mr Otterbourne seemed unable to grasp the utilitarian value of thermionic emissions and I was probably more abrupt than the occasion demanded.’ He glanced up. ‘You might have heard the process referred to as