Third Girl by Agatha Christie

bus and went straight up to the top. Mrs Oliver got inside and was able to get a seat close to the door as the uncomfortable third person.
    When the conductor came round for fares Mrs Oliver pressed a reckless one and sixpence into his hand. After all, she had no idea by what route the bus went or indeed how far the distance was to what the cleaning woman had described vaguely as “one of those new buildings by St Paul's”. She was on the alert and ready when the venerable dome was at last sighted. Any time now, she thought to herself and fixed a steady eye on those who descended from the platform above. Ah yes, there came Claudia, neat and chic in her smart suit. She got off the bus. Mrs Oliver followed her in due course and kept at a nicely calculated distance.
    “Very interesting,” thought Mrs Oliver. “Here I am actually trailing someone! Just like in my books. And, what's more, I must be doing it very well because she hasn't the least idea.”
    Claudia Reece-Holland, indeed, looked very much absorbed in her own thoughts.
    “That's a very capable looking girl,” thought Mrs Oliver, as indeed she had thought before. “If I was thinking of having a go at guessing a murderer, a good capable murderer, I'd choose someone very like her.”
    Unfortunately, nobody had been murdered yet, that is to say, unless the girl Norma had been entirely right in her assumption that she herself had committed a murder.
    This part of London seemed to have suffered or profited from a large amount of building in the recent years. Enormous skyscrapers, most of which Mrs Oliver thought very hideous, mounted to the sky with a square matchbox-like air.
    Claudia turned into a building. “Now I shall find out exactly,” thought Mrs Oliver and turned into it after her. Four lifts appeared to be all going up and down with frantic haste. This, Mrs Oliver thought, was going to be more difficult. However, they were of a very large size and by getting into Claudia's one at the last minute Mrs Oliver was able to interpose large masses of tall men between herself and the figure she was following.
    Claudia's destination turned out to be the fourth floor. She went along a corridor and Mrs Oliver, lingering behind two of her tall men, noted the door where she went in. Three doors from the end of the corridor.
    Mrs Oliver arrived at the same door in due course and was able to read the legend on it. “Joshua Restarick Ltd” was the legend it bore.
    Having got as far as that Mrs Oliver felt as though she did not quite know what to do next. She had found Norma's father's place of business and the place where Claudia worked, but now, slightly disabused, she felt that this was not so much of a discovery as it might have been.
    Frankly, did it help? Probably it didn't. She waited around a few moments, walking from one end to the other of the corridor looking to see if anybody else interesting went in at the door of Restarick Enterprises. Two or three girls did but they did not look particularly interesting.
    Mrs Oliver went down again in the lift and walked rather disconsolately out of the building. She couldn't quite think what to do next. She took a walk round the adjacent streets, she meditated a visit to St Paul's.
    “I might go up in the Whispering Gallery and whisper,” thought Mrs Oliver. “I wonder now how the Whispering Gallery would do for the scene of a murder?”
    “No,” she decided, “too profane, I'm afraid. No, I don't think that would be quite nice.” She walked thoughtfully towards the Mermaid Theatre. That, she thought, had far more possibilities. She walked back in the direction of the various new buildings. Then, feeling the lack of a more substantial breakfast than she had had, she turned into a local cafй.
    It was moderately well filled with people having extra late breakfast or else early “elevenses”. Mrs Oliver, looking round vaguely for a suitable table, gave a gasp.
    At a table near the wall the girl Norma was sitting,