They Do It With Mirrors by Agatha Christie

Christian Gulbrandsen has been found shot dead.'
    'Good God,' Alex registered a more than life-size dismay. 'Suicide, do you mean?'
    Carrie Louise moved swiftly.
    'Oh no,' she said. 'It couldn't be suicide. Not Christian! Oh no.'
    'Uncle Christian would never shoot himself, I'm sure,' said Gina.
    Alex Restarick looked from one person to the other.
    From his brother Stephen he received a short confirmative nod. Walter Hudd stared back at him with faint resentment. Alex's eyes rested on Miss Marple with a sudden frown. It was as though he had found some unwanted prop on a stage set.
    He looked as though he would like her explained. But nobody explained her, and Miss Marple continued to look an old, fluffy and sweetly bewildered old lady.
    'When?' asked Alex. 'When did this happen, I mean?'
    'Just before you arrived,' said Gina. 'About - oh three or four minutes ago, I suppose. Why, of course, we actually heard the shot. Only we didn't notice it - not really.'
    'Didn't notice it? Why not?'
    'Well, you see, there were other things going on...' Gina spoke rather hesitantly.
    'Sure were,' said Walter with emphasis.
    Juliet Bellever came into the Hall by the door from the library.
    'Mr Serrocold suggests that we should all wait in the library. It would be convenient for the police. Except for Mrs Serrocold. You've had a shock, Cara. I've ordered some hot bottles to be put in your bed. I'll take you up and -'
    Rising to her feet, Carrie Louise shook her head.
    'I must see Christian first,' she said.
    'Oh no, dear. Don't upset yourself -'
    Carrie Louise put her very gently to one side.
    'Dear Jolly - you don't understand.' She looked round and said, 'Jane?'
    Miss Marple had already moved towards her.
    'Come with me, will you, Jane.'
    They moved together towards the door. Dr Maverick, coming in, almost collided with them.
    Miss Bellever exclaimed:
    'Dr Maverick. Do stop her. So foolish.'
    Carrie Louise looked calmly at the young doctor. She even gave a tiny smile.
    Dr Maverick said:
    'You want to go and - see him?'
    'I must.'
    'I see.' He stood aside. 'If you feel you must, Mrs Serrocold. But afterwards, please go and lie down and let Miss Bellever look after you. At the moment you do not feel the shock, but I assure you that you will do so.'
    'Yes. I expect you are right. I will be quite sensible. Come, Jane.'
    The two women moved out through the door, past the foot of the main staircase and along the corridor, past the dining-room on the right and the double doors leading to the kitchen quarters on the left, past the side door to the terrace and on to the door that gave admission to the Oak suite that had been allotted to Christian Gulbrandsen. It was a room furnished as a sitting-room more than a bedroom, with a bed in an alcove to one side and a door leading into a dressing-room and bathroom.
    Carrie Louise stopped on the threshold. Christian Gulbrandsen had been sitting at the big mahogany desk with a small portable typewriter open in front of him. He sat there now, but slumped sideways in the chair. The high arms of the chair prevented him from slipping to the floor.
    Lewis Serrocold was standing by the window. He had pulled the curtain a little aside and was gazing out into the night.
    He looked round and frowned.
    'My dearest, you shouldn't have come.'
    He came towards her and she stretched out a hand to him. Miss Marple retreated a step or two.
    'Oh yes, Lewis. I had to - see him. One has to know just exactly how things are.'
    She walked slowly towards the desk.
    Lewis said warningly:
    'You mustn't touch anything. The police must have things left exactly as we found them.'
    'Of course. He was shot deliberately by someone, then?'
    'Oh yes.' Lewis Serrocold looked a little surprised that the question had even been asked. 'I thought - you knew that?'
    'I did really. Christian would not commit suicide, and he was such a competent person that it could not possibly have been an accident. That only leaves -' she hesitated a moment -