The Flat Stanley Collection. Jeff Brown

are the worst kind. They work by sneakery, which makes them very difficult to catch. However, my men and I will keep trying. Meanwhile, I hope people will buy tickets for the Policemen’s Ball and not park their cars where signs say don’t.”’

      The next morning Stanley Lambchop heard Mr Dart talking to his wife in the lift.

      ‘These sneak thieves work at night,’ Mr Dart said. ‘It is very hard for our guards to stay awake when they have been on duty all day. And the Famous Museum is so big we cannot guard every picture at the same time. I fear it is hopeless, hopeless, hopeless!’

      Suddenly, as if an electric light bulb had lit up in the air above his head, giving out little shooting lines of excitement, Stanley Lambchop had an idea. He told it to Mr Dart.

      ‘Stanley,’ Mr Dart said, ‘if your mother will give her permission, I will put you and your plan to work this very night!’

      Mrs Lambchop gave her permission.

      ‘But you will have to take a long nap this afternoon,’ she said. ‘I won’t have you up till all hours unless you do.’

      That evening, after a long nap, Stanley went with Mr Dart to the Famous Museum. Mr Dart took him into the main hall, where the biggest and most important paintings were hung. He pointed to a huge painting that showed a bearded man, wearing a floppy velvet hat, playing a violin for a lady who lay on a couch. There was a half-man, half-horse person standing behind them, and three fat children with wings were flying around above. That, Mr Dart explained, was the most expensive painting in the world!

      There was an empty picture frame on the opposite wall We shall hear more about that later on.

      Mr Dart took Stanley into his office and said, ‘It is time for you to put on a disguise.’

      ‘I had already thought of that,’ Stanley Lambchop said, ‘and I brought one. My cowboy suit. It has a red bandanna that I can tie over my face. Nobody will recognise me in a million years.’

      ‘No,’ Mr Dart said. ‘You will have to wear the disguise I have chosen.’

      From a closet he took a white dress with a blue sash, a pair of shiny little pointed shoes, a wide straw hat with a blue band that matched the sash, and a wig and a stick.

      The wig was made of blonde hair, long and done in ringlets. The stick was curved at the top and it, too, had a blue ribbon on it. Stanley was so disgusted that he could hardly speak. ‘I shall look like a girl, that’s what I shall look like,’ he said. ‘I wish I had never had my idea.’

      But he was a good sport, so he put on the disguise.

      ‘In this shepherdess disguise,’ Mr Dart said, ‘you will look like a painting that belongs in the main hall. We do not have cowboy pictures in the main hall.’

      Back in the main hall Mr Dart helped Stanley climb up into the empty picture frame. Stanley was able to stay in place because Mr Dart had cleverly put four small spikes in the wall, one for each hand and foot.

      The frame was a perfect fit. Against the wall, Stanley looked just like a picture.

      ‘Except for one thing,’ Mr Dart said. ‘Shepherdesses are supposed to look happy. They smile at their sheep and at the sky. You look fierce, not happy, Stanley.’

      Stanley tried hard to get a faraway look in his eyes and even to smile a little bit.

      Mr Dart stood back a few feet and stared at him for a moment. ‘Well,’ he said, ‘it may not be art, but I know what I like.’

      He went off to make sure that certain other parts of Stanley’s plan were being taken care of, and Stanley was left alone.

      It was very dark in the main hall. A little bit of moonlight came through the windows, and Stanley could just make out the world’s most expensive painting on the opposite wall. He felt as though the bearded man with the violin and the lady on the couch and the half-horse person and the winged children were all waiting, as he was, for something to happen.

      Time passed and he got tireder and tireder. Anyone would be tired this late at night, especially if he had to stand in a picture frame balancing on little spikes.

      Maybe they won’t come, Stanley thought. Maybe the sneak thieves won’t come at all.

      The moon went behind a cloud and then the main hall was pitch dark. It seemed to get quieter, too, with the darkness. There was absolutely no sound at all. Stanley felt the hair on the back of his neck prickle beneath the golden curls of the wig.

      Cr-eee-eee-k . . .

      The creaking sound came from right out in the middle of the main hall and even as he heard it Stanley saw, in the same place, a tiny yellow glow of light!

      The creaking came again and the glow got bigger. A trap door had opened in the floor and two men came up through it into the hall!

      Stanley understood everything all at once. These must be the sneak thieves! They had a secret trap door entrance into the museum from outside. That was why they had never been caught. And now, tonight, they were back to steal the most expensive painting in the world!

      He kept very still in his picture frame and listened to the sneak thieves.

      ‘This is it, Max,’ said the first one. ‘This is where we art robbers pull a sensational job whilst the civilised community sleeps.’

      ‘Right, Luther,’ said the other man. ‘In all this great city there is no one to suspect us.’

      Ha, ha! thought Stanley Lambchop. That’s what you think!

      The sneak thieves put down their lantern and took the world’s most expensive painting off the wall.

      ‘What would we do to anyone who tried to capture us, Max?’ the first man asked.

      ‘We would kill him. What else?’ his friend replied.

      That was enough to frighten Stanley, and he was even more frightened when Luther came over and stared at him.

      ‘This sheep girl,’ Luther said. ‘I thought sheep girls were supposed to smile, Max. This one looks scared.’

      Just in time, Stanley managed to get a faraway look in his eyes again and to smile, sort of.

      ‘You’re crazy, Luther,’ Max said. ‘She’s smiling. And what a pretty little thing she is, too.’

      That made Stanley furious. He waited until the sneak thieves had turned back to the world’s most expensive painting, and then he shouted in his loudest, most terrifying voice: ‘POLICE! POLICE! MR DART! THE SNEAK THIEVES ARE HERE!’

      The sneak thieves looked at each other. ‘Max,’ said the first one, very quietly, ‘I think I heard the sheep girl yell.’

      ‘I think I did too,’ said Max in a quivery voice. ‘Oh, boy! Yelling pictures. We both need a rest.’

      ‘You’ll get a rest, all right!’ shouted Mr Dart, rushing in with the Chief of Police and lots of guards and policemen behind him. ‘You’ll get arrested, that’s what! Ha, ha, ha!’

      The sneak thieves were too mixed up by Mr Dart’s joke and too frightened by the policemen to put up a fight. Before they knew it, they had been handcuffed and led away to