Mr. Tangent stood at the blackboard. He was drawing a triangle.

"Pythagoras," Mr. Tangent said. "A squared plus B squared equals C squared. The hypotenuse is the longest side. It is the direct path. The shortcut."

Alex sat at his desk. He looked at the triangle.

He did not see lines. He saw passing lanes.

A is the winger. B is the midfielder. C is the through ball.

"Mr. Finch," Mr. Tangent asked. "If side A is 30 yards and side B is 40 yards, what is the length of C?"

Alex blinked. He thought about the football pitch.

"Fifty yards, Sir," Alex said. "But only if you put enough backspin on the ball to account for friction."

"Just fifty, Alex," Mr. Tangent sighed. "Please leave friction out of geometry."

Mark sat next to Alex. Mark was wearing a pair of glasses with no glass in them. He looked very studious, or very confused.

"I like triangles," Mark whispered.

"Really?" Alex asked.

"Yes," Mark said. "Pizza is a triangle. Nachos are triangles. Triangles are the tastiest shape."

"It is geometry, Mark. Not lunch."

"Everything is lunch if you are hungry enough," Mark said wisely.

The bell rang.

Alex packed his bag.

School was done. But the real geometry test was waiting.

Champions League. Quarter Finals.

AC Milan. Away.

The San Siro.

It was one of the cathedrals of football. A giant, concrete beast in Italy.

Alex walked out to the car park.

Milo was waiting.

Milo was not wearing a costume this time. He was wearing a suit.

But it was not a normal suit. It was made entirely of glossy magazine pages taped together. He looked like a walking billboard.

"THE FASHIONISTA!" Milo shouted. "MILAN IS THE CITY OF STYLE! ALEX! LOOK AT ME! I AM HIGH FASHION! I AM SELLING DESIGNER SOCKS! THEY HAVE HOLES IN THE TOES FOR AERODYNAMICS! ONE HUNDRED EUROS A PAIR!"

"Milo, you look like a recycling bin," Alex said.

"IT IS CALLED DERELICTE!" Milo yelled, striking a pose. "IT IS THE FUTURE! BUY NOW BEFORE VOGUE CALLS ME!"

They drove to the airport.

Mark was sitting in the back. He was wearing a scarf. A very long scarf. It was wrapped around his neck six times.

"Why the scarf, Mark?" Alex asked.

"Italian style," Mark said, muffling his voice. "I am blending in. I am practically a local. Ciao. Pizza. Ferrari."

"You are going to trip over it," Alex warned.

"Fashion is pain," Mark replied.

Italy. Milan.

The city was beautiful. But the stadium was intimidating.

The San Siro was huge. It had spiral towers in the corners. It looked like a fortress built by giants.

Steve, the manager, stood in the dressing room.

"Milan," Steve said. "The Rossoneri. Seven times champions. They have history in the walls."

He pointed to the screen.

"They defend well. Tomori. Hernandez. Maignan. They are tough."

He clicked the remote. A video of a player running appeared. He was tall, languid, and smiling.

"Rafael Leao," Steve said. "He is the danger. He smiles when he dribbles. He is fast. Maybe the only player who can race Mark."

Mark looked up from tying his shoelaces.

"Race me?" Mark scoffed. "Does he have a rocket on his back?"

"No," Steve said. "He has rhythm. He dances past people."

"I dance too!" Mark said. "I do the robot!"

"Just run, Mark," Steve said. "Professor. Find the angles. Milan is narrow. They protect the middle. Find the hypotenuse."

"The long diagonal," Alex nodded. "I see it."

They walked out of the tunnel.

The noise was different here. It was deep. A roar that came from the belly of the stadium.

Milan! Milan!

Alex stood next to Rafael Leao.

Leao was chewing gum. He looked at Alex. He smiled. It was a cool smile.

"Wonderkid," Leao said.

"Surfer," Alex replied (because Leao did a surfing celebration).

"Catch me if you can," Leao winked.

"We will see," Alex said.

The whistle blew.

The game started.

Milan was disciplined. They sat in a tight shape. Compact.

Arsenal tried to play short passes.

Tick. Tock.

But the Milan midfield, Bennacer and Tonali, were aggressive. They bit into every tackle.

In the tenth minute, Milan countered.

Theo Hernandez won the ball. He smashed it forward.

Leao was running.

Ben White tried to stop him.

Leao did a stepover. Then another. He looked like he was dancing to music only he could hear.

He pushed the ball past Ben White.

He sprinted.

"He is fast!" Jude yelled.

Leao cut inside. He opened his body.

He curled the ball into the far corner.

Goal.

One zero. Milan.

Leao ran to the corner. He pretended to surf on the grass.

The San Siro exploded. Flares were lit. Smoke drifted across the pitch.

Alex stood in the center circle.

One zero down.

"He surfs well," Mark admitted. "But can he fly?"

"We need triangles," Alex said. "Mark. Stay wide. Stretch the pitch. Make side A longer."

"I hate math!" Mark shouted. "But okay!"

Arsenal restarted.

Alex changed the geometry.

He stopped playing short. He started looking for the hypotenuse.

Thirty minutes passed.

Alex got the ball deep.

Tonali came to press him.

Alex waited. He saw Mark hugging the touchline on the right.

The distance was fifty yards.

Alex hit the pass.

It was a diagonal laser. It flew over the head of Theo Hernandez.

Mark controlled it.

He was one on one with Hernandez.

"RACE TIME!" Mark screamed.

Mark pushed the ball. Hernandez turned and ran.

It was a blur. Blue vs Red.

Mark was faster. Just.

He got to the byline. He crossed it.

Saka was there.

Saka volleyed it.

Maignan made a save! The Milan goalkeeper was a cat.

"How?" Saka yelled. "It was in!"

"Keep going!" Alex shouted. " The angle was right!"

Halftime. One zero.

Steve was calm.

"You found the weakness," Steve said. "The diagonal ball kills them. Hernandez attacks, so he leaves space behind. Attack the space."

He looked at Alex.

"Professor. Calculate the trajectory. Put it on a plate."

Second half.

Milan dropped deeper. They wanted to protect the lead.

This made it harder. The spaces were smaller.

Sixty minutes. Seventy minutes.

Alex was tired. The Italian midfielders were physical. They pulled shirts. They stepped on toes.

Seventy fifth minute.

Alex had the ball.

He looked forward.

The red and black wall was solid.

He looked at Mark. Mark was waving his arms.

But Alex saw something else.

He saw Jude Bellingham making a run from deep.

But there was no passing lane. Tomori was in the way.

Alex remembered the math class.

Pythagoras. The direct path.

But sometimes, in football, the direct path is blocked.

You need a curve.

Alex looked at the goal.

He was thirty yards out.

He did not pass.

He shot.

But it was not a normal shot. It was a "Trivela". The outside of the boot.

He hit the ball on the right side.

The ball started to go wide. It looked like it was going to the corner flag.

Tomori turned his head to watch it go out.

But then, the spin took over.

The ball swerved. It bent back in.

It curved around the defender.

It curved around the goalkeeper.

It hit the post.

CLANG.

It bounced out.

But Jude was there. The Power.

Jude reacted first. He tapped the rebound into the net.

Goal.

One one.

The Arsenal fans in the top tier cheered.

Alex raised his hand. "Calculated geometry."

Jude grabbed him. "That curve! It defied logic!"

"It was a parabola!" Alex laughed.

Milan was angry now. They attacked.

Eighty fifth minute.

Leao got the ball again. He smiled. He ran.

He beat Saliba. He beat Gabriel.

He was through.

Ramsdale came out.

Leao shot.

Ramsdale saved it with his foot!

The ball flew high into the air.

Alex controlled it on his chest.

He looked up.

It was a counter attack.

The Milan defense was disorganized.

Mark was running. He was on the halfway line.

Alex hit the ball.

A long, high ball.

Mark ran.

Theo Hernandez ran.

"TURBO BOOST!" Mark screamed.

Mark got to the ball first.

He was thirty yards from goal. Maignan was rushing out.

Mark did not shoot.

He stopped.

He put his foot on the ball.

Hernandez slid past him. Maignan slid past him.

They both ended up in a heap on the floor.

Mark stood alone with the ball. The goal was empty.

Mark walked the ball to the line.

He stopped again.

He lay down on the ground.

He headed the ball over the line while lying down.

Goal.

Two one. Arsenal.

Mark stayed on the ground. He did a swimming motion.

"I AM SURFING TOO!" Mark yelled. "BUT I AM SURFING ON THE FLOOR! IT IS CALLED GRAVITY SURFING!"

The San Siro went silent.

Alex ran over. "Mark, stand up. You look like a fish."

"I am a shark!" Mark said, jumping up. "A fast shark!"

The final whistle blew.

Arsenal 2. AC Milan 1.

They had conquered the San Siro.

Alex walked off the pitch.

Leao walked over. He was still smiling, but it was a sad smile.

"You are good," Leao said. "You have eyes in your feet."

"And you are fast," Alex said. "See you in London."

Milo ran onto the pitch.

His magazine suit was ripped.

"THE PAPER BOY!" Milo shouted. "EXTRA! EXTRA! READ ALL ABOUT IT! ALEX! THE CURVE! I AM SELLING ORIGAMI! I FOLDED THE PROGRAM INTO A SWAN! IT IS WORTH MILLIONS!"

"Milo, did you rip your suit?" Alex asked.

"IT IS DISTRESSED FASHION!" Milo insisted. "VERY EXPENSIVE!"

They walked into the dressing room.

The team was celebrating. Pizza boxes were already there.

Alex sat down. He was exhausted.

He checked his phone.

A text from Maya.

"Geometric analysis: Perfect. The angle of your shot was 42 degrees. The curve deviation was 1.5 meters. You solved for X, where X is the back of the net. Also, Mr. Tangent sent an email. He wants to know if you can calculate the volume of a sphere for tomorrow's homework."

Alex laughed.

"A sphere," Alex whispered. "Like a football."

He looked at Mark.

Mark was wearing a pizza box as a hat. He was eating a slice.

"Hey Professor," Mark said.

"Yeah?"

"Did you see me surf?"

"I saw you flop," Alex said.

"It was style," Mark said. "Milan style. I am a fashion icon."

Alex shook his head.

They were in the Semi-Finals. Again.

The Dynasty was rolling.

And the Professor had solved another problem.

"One more step," Alex said to himself.

He took a slice of pizza.

It was a triangle.

"Pythagoras was right," Alex smiled. "Triangles are delicious."