‘The diary may prove to be a vital source. There are two possibilities here. Either the murderer knew about the third book and has taken it or destroyed it there in the flat, which is perfectly plausible. Getting hold of the diary may in fact have been the motive for murdering Harald Olesen in the first place, if the murderer knew about the diary and that it contained something important. But Harald Olesen was obviously very concerned that the diary should not fall into the wrong hands, so it is also perfectly possible, and highly likely, that the murderer never even saw the diary, that he or she did not know of its existence and therefore did not look for it. In which case, the diary is still where Harald Olesen hid it in the flat.’
I made a feeble protest on behalf of the police.
‘Please do not completely underestimate us! We have searched the flat and would of course have acted immediately had we found a handwritten diary.’
Patricia had a ready answer.
‘Of course, I have absolute confidence in the police. But firstly, you had no idea that there was a diary to look for, and secondly, a diary is relatively easy to hide. Again there are two possibilities: Harald Olesen may have hidden it in a secret compartment in his bedside table or wardrobe or suchlike-’
I interrupted her with an indignant protest.
‘I would like to see such a compartment: we have knocked on and measured every wall in every room!’
Patricia still did not seem entirely convinced, but changed tack.
‘In that case, the question is whether you checked the best hiding place for a diary.’
She on purpose said no more, thereby forcing me to ask.
‘And where do you think is the best place to hide a diary?’
Her answer was followed by delighted laugher.
‘Why, in the bookshelf, of course. I should imagine that you made a list of all the book titles, but did any of you check that none of them contained a diary?’
I had to admit to myself that we had done neither, but I did not say a word, just made a mental note that we should look through the bookcases and the rest of the flat again, given the news of the missing diary. We agreed in all haste that this was what I should do and then go to see her at around seven. I spontaneously said ‘yes, please’ to a light supper. She asked me to take the diaries with me and any other papers that might be relevant, and to go and see the caretaker in hospital on the way. She then assured me that it would not be a problem if I was late: she had no plans to go anywhere today. I could still hear her slightly smug laughter ringing in my ears as I gathered up my papers and the diaries and headed for the door.