"It is just like a woman to be foolish. It is just like a man to encourage her."

-Andrew Hamilton in 'A Treatise on the Duties of the Female Sex' (1797)

The late May sunshine soaked London in a buttery light, turning the buildings into golden coins. Clara met the boys at the entrance to Knightsbridge tube station; Jack was leaning against the railing, whistling a cheery tune under his breath. Liam, on the other hand, looked like he was about to be sick in a bin. Clara raised an eyebrow.

"You okay, Pemberton?" she called.

He waved her off. "Dodgy salmon for breakfast."

She didn't believe him. Not for a second. "I thought you were vegetarian now."

"Pescatarian," Liam said.

Clara pressed a hand to her chest. "Fish are animals, too, Liam."

Liam muttered something that didn't sound particularly pleasant under his breath, starting for the stairs. The station was an anthill of chaos; they dodged around tourists carrying shopping bags and briefcase-wielding businessmen. Several people glared as they shouldered their way down the platform, stopping directly in front of an advert for whitening toothpaste. The billboard was so faded with age that the woman's teeth had, ironically, started to look a little yellow.

Liam moaned as the train rolled into view.

"I can't do it." He leaned forward, resting his hands on his knees. "I think I'm going to be sick."

Jack patted his back. "Let the salmon swim free."

Clara kicked his ankle. "Gross, Ogs."

They stepped into the last compartment. It was mostly empty, the only occupants being a woman carrying a dog and a man that bore an odd resemblance to a toad. Clara was still considering this when the tube passed through a station that was out of service. The artificial light cast a greenish tinge on the white stonewalls, making it look as if the entire station was underwater.

"Here we go," Liam muttered.

Clara had done this a million times before, but nothing quite prepared you for the strange sucking sensation of time slowing down. It felt like the entire world around you had turned gummy. The air became thicker, almost oppressive, and she felt her stomach lurch. Jack, who had never quite gotten over time travel sickness, looked a bit green as they exited the train. Clara paused on the platform, glancing over her shoulder as the train sped up and time compressed once more.

"Thank god," Jack said, with some feeling.

Clara hit the button on the lift. "You're such a baby."

"Easy, Eaton," Jack said. "I'm not the one that got sick in the taxi on our way home from the club last week."

And Clara, who could not deny it, remained silent.

The exams were brutal.

Then again, Clara thought, she'd been expecting it; Jack, Liam and herself were the only three students graduating this year. Andrew Winchester and three students from non-POWER families had been the year above them, and the next two students graduating – Emma and Hazel, Jack's younger sister – would be in three years' time. And while the instructors were fair, their expectations were...

Well.

'High' seemed too kind a word.

The written exam was first. The test was divided into two parts: basic comprehension, and then the area that you were specializing in. Clara blew through the basics (what's the longest jump you can do? Forty-eight hours, until you were pulled back to the present), but the part on Ancient Greece was more difficult. She mixed up Pythagoras and Ptolemy, but she managed to save it by writing a decent essay (in her opinion, anyway) on the difference between Doric and Corinthian columns.

The language test went okay as well, although Clara forgot the Greek word for invader. She passed the simulation with flying colors (she'd always been good at sneaking into temples) and the reading comprehension wasn't a disaster, either.

The combat test was last.

It was complicated, as far as final exams went; the goal was to deliver a child to safety while fighting off five sword-wielding attackers, all while suspended on wooden blocks that dangled ten-feet off the ground. Oh, and you could only use one hand, because the other one was holding the child (in reality, a sack of potatoes from Tesco).

Which, you know. Not ideal.

Jack finished the obstacle course in three minutes and forty-two seconds, with only a minor stab wound to the knee. Liam finished in three minutes and forty seconds, but he'd also dropped the sack of potatoes over the edge of the rope bridge, which meant that — technically — he had killed the child.

Clara finished in two minutes and thirty-nine seconds, flipping off the rafters with the sack of potatoes in hand. One of the instructors had cheered. Actually cheered. Even her father had given her a gruff "well done," patting her on the shoulder.

It was, hands-down, the best moment of her life.

There had been a celebratory dinner after at the Ogilvy's manor, followed by a celebratory round of drinks with all five families. It was only after the celebratory cake and celebratory candles that Jack, Liam, and Clara were finally set free. It was, after all, their muck-up day, and even their parents respected the tradition.

"Make it good," Marie murmured, squeezing her hand. "If I have to listen to Sarah Winchester bang on about how clever Andrew was to set chickens loose in the building one more time, I'll smother her to death."

Clara winked. "Don't worry. I'll make you proud."

An hour later, Clara was stealing through the Headquarters, a knapsack of explosives thrown over her back. Jack was humming, jumping every few feet as he attempted to only walk on the black tiles. Liam, on the other hand, was starting to look a bit ill. His glasses were fogged from his heavy breathing, and he let out a low moan as they turned a corner, like a wounded animal caught in a trap.

"If this goes wrong," Liam muttered, "I'm blaming you."'

Clara shifted the knapsack. "It won't."

"This is a bad idea."

"Do we ever have good ones?" Jack asked, which was, Clara had to admit, a fair point. He reached over to flick the knapsack, grinning as Liam winced. "Chill, Pemberton. It's not like it's going to explode."

"Actually," Liam said, "that's exactly what it's going to do."

Jack hopped to another black tile. "Okay. It's not going to be a big explosion."

"How comforting," Liam muttered.

They climbed the narrow, spiraling stairs in silence, listening to the sound of Liam's ragged breathing. The passageway was lit only by the yellow flicker of candles, and Clara had to squint to see through the darkness. Liam would have kittens if she tripped with the explosives on her back. But Clara wasn't worried; between swimming in the Thames in January, fighting Spanish conquistadors, and tumbling out of third-story windows without a rope, she had built up a healthy dose of self-confidence. Carrying explosives wasn't even the riskiest thing she had done this week.

Still, Clara took care as she drew a key out of her pocket, unlocking the door so she could step on to the landing. It wouldn't do to accidentally blow-up part of the British government. That would be a very awkward chat with her father.

"Christ," Jack breathed. "Has this staircase gotten smaller?"

He was half-leaning against the wall, one hand pressed against the stone. Clara glanced back at him.

"No," Clara said. "You're just claustrophobic."

Jack gave her a wounded look. "I am not."

She arched an eyebrow. "Don't you remember that time we did a walking tour of Mary King's Close in Edinburgh? You made it about ten feet into the underground city before you burst into tears. Mum had to get you an ice cream."

"I was six," Jack said.

"So? That doesn't mean—"

"Eaton," Liam said, massaging his temples. "Can you please not argue with Ogs while you're carrying explosives?"

Clara rolled her eyes. Still, she was silent as they stepped into the room. Liam had a point; not that she was about to admit it to him.

Clara swung the backpack off her shoulders, ignoring Liam's yelp of protest. All four fireworks were intact, thankfully. She unpacked them one-by-one onto the floor of the clock tower, taking care not to jostle them. The tower was the only part of Headquarters that rose above ground (by thirteen-and-a-half stories, in fact; Clara had counted when she was making her calculations), and it was dominated by the large, roman numeral clock built into the windows in the far wall. Through the clock, Clara could see the British parliament buildings like a candle in the night sky, rising above the black water of the Thames.

So, apparently, could Liam because he began to sweat profusely. "Don't touch the clock."

Clara gave him a look. "Obviously."

It was the first thing every new student learned, even before don't run in the tube station and don't climb up the stairs with explosives. The clock was the only way that time travellers could jump through time. It took decades to learn how to get the settings right for the jump (and for the traveller's return), which meant that novices were banned from the clock tower without very strict supervision.

Absently, Clara patted the key in her pocket.

Good thing Director Eaton was her father.

"Hurry up, Eaton," Jack said, yawning. "It's nearly midnight."

"Right."

She began to pull out cannisters more swiftly, passing all four to Jack. He lifted them in his hand, as if testing the weight, and Clara smiled. They made a good team: Liam had the chemical knowledge to build the fireworks, Clara had the balls to carry them, and Jack had the technical skills to throw them through the window without hitting the clock.

Speaking of which.

Clara hit a switch on the wall. She could feel her heart hammering as the window melted away, letting a breeze into the room. She grinned at the boys.

"Care to do the honours?" she asked.

Jack fiddled with the cannister. There was a bang and then a missile shot through the window, exploding into red and gold showers in the darkness. Clara let out a whoop of laughter, punching a fist into the air. Even Liam was smiling.

"You're such idiots," Liam said, shaking his head. "I can't believe I'm friends with you."

There was another pop, and then blue sparks coloured the night sky. Turquoise wheels exploded next, then silver teardrops, fuchsia lightning, and violet rain. Clara was laughing so hard that she could hardly breathe.

"Last one," Jack said, smirking. "Prepare to be amazed."

Clara gave him a thumbs-up. "I'm ready."

"If you thought that performance was exciting," Jack said, waving the last canister, "just wait until you see—"

"Ogs!" Clara was vibrating with impatience. "Do it!"

He laughed, loud and clear, and then fired the rocket. But something wasn't quite right, Clara realized, her chest tightening; the angle was off. Her mind worked feverishly, running through rapid calculations. Within a split-second of impact, she understood what was going to happen: the rocket wasn't going through the window.

It was going to hit the clock.

Clara didn't think. She moved.

Her arm struck the clock. White-hot pain exploded up her arm, knocking the breath from her lungs. Someone shouted her name. The world seemed to slide, and the arrows on the crystal clock began to spin in all directions, a whir of helicopter blades.

Mum, Clara thought. I'm sorry.

Then everything was dark.