The science museum smelled of metal and polish, sunlight striping the floor beneath the glass roof. The school group moved in a quiet ribbon between displays, voices low, teachers watchful.
Emma walked with Oliver and Lucy, notebook under her arm. Jack and Amira drifted behind. Everything felt calm and ordinary. Arthur kept to the back, rucksack half open, wires and tools spilling out. He was the boy who built balancing robots for fun, who spoke in code and circuits more than words.
In the gallery of forgotten inventors, Arthur stopped. A small brass box sat inside a display case, engraved with gears and tiny holes. He crouched to study it, eyes sharp.
“What is it doing here?” he murmured. He picked up a scrap of paper beside it – two lines of writing, a block of code. He read it once, folded it and quickly hid it in his pocket. “I’ll be back
No one noticed at first. Then, during the headcount after lunch, his name was missing. The teacher’s voice cracked. “He was right here. We must find him.
They searched the galleries methodically: the electricity wing with its humming coils, the robotics lab with rows of inert arms, the replica Victorian engine room. No sign. Only Arthur’s rucksack, abandoned by a bench near the display of early calculators, zipped half open as if waiting for him to return.
Oliver crouched, fingertips hovering over the rucksack. “His bread roll is still inside,” he said. His voice was steady, but his eyes were quick. “He didn’t stop for lunch. He followed something
Emma felt a hollow pull in her chest. Curiosity had always been a kind of law among them – it trailed each of the detectives like a shadow. If Arthur had been pulled away by curiosity
The first clue was small. It was the brass box in the gallery, left unlocked now that officials had scanned it. Inside, beneath a layer of embroidered velvet, sat a folded slip of paper and a tiny mechanical puzzle – the kind that turned like a brain. The paper held a short, clipped riddle and two equations, written in a hand that felt familiar and precise.
“Two gears and a spring, a simple test,
Equations: G + G + 4 = 18; G − 2 = K. Find G × K.
Emma set the puzzle on her palm like a warm pebble. It clicked when she turned it. The children clustered; the museum’s quiet shivered around the tiny voice of the riddle.
❌ Work step by step. Solve for G first using the first line, then substitute to find K. A common mistake is to try to guess both at once. Instead, isolate one variable.
✅ Excellent! You certainly understand algebra.
Emma read the number aloud. Jack tapped it with his knuckle. “Thirty-five,” he said. “Maybe it’s a label. Look – the thirty-fifth panel along the corridor, the one with the old neon sign. That must be it.”
They followed the number through a corridor of exhibits until it brought them to a small map of workshops on the floor plan: a route to a closed section called the Conservator’s Bay. The map’s diagram showed a short passage and a model of a room. Tucked into the corner of the model was a second scrap with a note: “Scale carefully
Jack examined the little model. The path from the small doorway to the central bench measured 120cm on the model. He raised an eyebrow. “If the model is 1:20, then what length in reality do 120 centimetres represent? No, wait.” He shook his head and checked it, even more carefully than before. Count steps
The model’s path measures 120 cm. The model scale is 1:20. Find how many steps that equals if one step is 0.8 m.
❌ Remember that you have three conversions to manage! First, use the 1:20 scale to find the actual length in centimetres. Then, convert that length into metres before you can finally divide by the length of one step.
✅ Great conversions!
They paced out thirty confident strides along the gallery floor where the Conservator’s Bay opened. A heavy door was ajar. Inside, under a sheet, something metallic hummed very faintly.
Beyond the sheet was a corridor of plexiglass cases. At the far end, a mirrored wall reflected the room a dozen times. On the floor in front of the mirror, an old floor tile had been marked with chalk coordinates: (−3, 5). A small etching beside it read: “Mirror the path, then step two right.” Lucy squinted at the chalk and tapped her pencil against her lip.
Take the point (−3, 5). Mirror it across the y-axis, then translate it by adding +2 to the x-coordinate.
❌ Remember that mirroring across the y-axis makes x become its opposite sign. Then apply the translation only after reflecting. A common error is to add the translation and then reflect – the order matters.
✅ Well done! Coordinates and transformations are certainly one of your strengths.
At the tile (5, 5), they lifted a loose corner of linoleum and found, taped underneath, a grainy black-and-white photograph of a tiny workshop stacked with gears and strings. A caption in careful script read: “Leonardo’s toy: the twin gear machine.” Beside it lay a folded page from a very old notebook with a number sequence scrawled in hurried pen: 7, 11, 19, 35, ?
“It looks almost like prime numbers,” Oliver said. “But not exactly. The differences between terms are growing.”
Emma chewed her lip. The sequence was jagged, like teeth.
❌ Examine the pattern of changes, not the numbers themselves. Try calculating the differences between successive terms and see if that reveals a rule. Often, sequences hide a pattern in their gaps.
✅ It looks like patterns and sequences can’t hide anything from you.
Tucked under the photograph was a brass cog with the number 67 faintly stamped on its rim. The cog fitted into a slot in the wall. When they pushed it home, the stained-glass window at the far end of the room began to glow as the afternoon sun shifted. The window was a riot of colour and small panes painted with schematic diagrams like little blueprints: gears, pulleys, tiny circuits. At its centre, a pattern of curved shapes repeated around a central point, like a flower turned inside out.
Outside the museum, the light softened. Inside, the stained glass rippled like liquid fire. At the lowest corner of the frame, a plate read: “Rotate until the circle is full.”
The window’s central motif repeats evenly as it turns around its centre smallest angle must you turn it to see the same pattern again?
❌ Remember that order means how many times a shape matches itself in one full turn. To find the rotation angle, divide 360° by the order of symmetry.
✅ Great job! You’ve mastered rotational symmetry and angles in a circle.
When the window clicked into place, a hidden panel in the display case slid open with a soft mechanical sigh. Behind it was a small hatch, and within, the faint hum of a device that felt like a heartbeat. Arthur crouched in the hatch, as if he had been sitting there a long while, quiet as a shut book. He looked up at them without surprise
“Arthur!” Emma breathed. Relief hit her like a wave. He stood as if he had been only resting between solving puzzles. He looked older than his years: unhurried, precise. He did not reach immediately for his rucksack.
“I saw my work,” he said, in that slow, careful voice. “Someone made a copy of my prototype and left it on the display. I wanted to see who had done it.”
Oliver nearly laughed from the strain of the last hour. “You were lured
Arthur’s eyes did not flicker. “It wasn’t a trap,” he said. “It was an invitation
Arthur’s story was clear as a blue sky, except for the small, nagging cloud of doubt hanging right over their heads. As they walked back toward the museum entrance, Emma replayed his words over and over. Something was off.
The museum felt very quiet; the galleries seemed to be holding their breath. The teacher approached, relieved and then, for a second, wildly animated. He praised the team and then, to Emma’s ear, muttered, “Well done. That was quick
They had solved every puzzle. They had found the missing boy. But instead of closure, Emma felt something turning in the dark, gears shifting behind walls they couldn’t see.
No cheers. No celebration. Just silence tightening around them like a noose. This wasn’t a rescue. This wasn’t an accident. This was a design.
Someone had left that trail for Arthur…and they had followed it too…
Emma’s spine prickled as doubts slowly surfaced followed by a burning question:.
What if this was never about Arthur being found? What if it was about seeing who would come after him?
Case not closed!
To be continued…
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