palace was, it seemed, constructed on a kind of giant woven raft, one made from bulrushes. It was incredible that such a mighty structure could sit securely as it did on a foundation so flimsy and feeble.
Scanning the zigzag lines between the blocks of stone, Rintin noticed that there was an unevenness near the waterline. A piece of marble had been wedged into a crack where the zigzag joins were broken, and a definite force was being exerted upon it. But, even stranger still, was the fact that a fragment of wood, no bigger than a matchbox, had been hammered into place beside the sliver of marble.
The wood was held in place with a nail, a bent brown rusty nail.
Touching a finger to his chin in contemplation, Rintin made a series of calculations.
By his reckoning, the entire palace was being held by this single nail.
How extraordinary, he thought, that the emperor’s mighty seat of power was so precariously in the balance, and all because a craftsman had cut a corner he imagined no one would ever spot.
Paddling his canoe over to the nail, Rintin knocked it up and down with his oar, until it was loose. Then, taking a deep breath, he pulled it away from the wood.
Nothing happened.
Not at first, anyway.
A minute passed. And another. The boy cupped a hand to his right ear. He had heard something – a faintest undertone of sound. He gasped, grabbed the oar, and paddled away as fast as he could.
A moment later, there was a deafening noise, as the zigzag joins began to part, and the palace began to fall.
Lost in his treasure vaults, the emperor was counting the sacks, ordering them to be rearranged in a new way.
All of a sudden he heard the sound of masonry collapsing in the distance.
‘What’s that?!’ he thundered.
His vizier swiped a hand through the air and oozed reassurance.
‘Surely it’s nothing, Your Importantness,’ he whispered unctuously. ‘But I will…’
Before he had time to finish his sentence, the floor of the treasure vault disappeared clean away beneath them.
The vizier, the emperor, and all the precious treasure, were plunged into the now choppy waters of the River Walaqa.
Spying their monarch struggling for his life, the guards fled, the palace nothing more than rubble around them. With the sun touching the horizon, the townspeople flocked to the imperial gate.
Rintin clapped his hands and addressed them.
‘You are free!’ he yelled. ‘And never again will you be prisoners!’
He held up the rusty nail, with a bend at one end.
‘This nail is a symbol that even the worst despot can be brought down in the simplest way. The great power is power that hangs by a thread.’
The crowd cheered.
Then a wizened old man pushed to the front.
Rintin recognised him as his neighbour, saved from the gallows in the nick of time.
‘This boy has saved us,’ the man exclaimed, ‘and so I vote that we make him our king!’
There were more cheers, and Rintin was carried at shoulder height through the streets. The emperor’s launch took him across to the island where he was reunited with his parents.
In due course Rintin was indeed made the king and he ruled for many years.
He married the little girl with the doll, and had six sons, each one wiser and more handsome than the last.
On his desk he kept an orb, and a walnut-coloured box.
And in the box he kept the nail.
After a great many years, King Rintin breathed his last, his beloved queen and many sons clustered around his bed. The royal family and their kingdom mourned the loss. And, according to his wishes, they buried their monarch in a simple grave on the island where the Slate Tower once stood.
In a letter left to his children, King Rintin decreed that the son with the keenest power of observation should follow him as ruler of the land.
‘But how shall we decide which that is?’ asked the queen.
The lord chamberlain, who was reading the letter aloud, motioned to the page.
‘“The one of you who can glimpse a secret level in a