“Gosh, Nancy. I thought the prison had swallowed you up and would never spit you out,” said Burch, his face pinched with worry.

Nancy slumped against the wall, gulping in deep breaths of night air as the guard bolted the side door behind her.

“What happened in there?” asked Burch.

Nancy quietly told him about meeting her aunt, who had been in the prison for such a long time and was married to the mayor.

Burch gasped. “Are you sure she was telling you the truth? I’ve lived in this town all my life and never heard anyone speak of the mayor’s wife.”

Nancy nodded. “I’m certain. Agatha looked so like Mother, there is no mistaking they are related. To think I have had an aunt all these years and knew nothing of her.”

“Poor Mr Greenstone, two of his daughters locked up in prison,” said Burch, whistling quietly through his teeth.

Nancy glanced at Burch. “Agatha didn’t say why she was in prison, but it can’t be a coincidence that my mother is now in there too. The mayor is behind this and I need to find out why and put a stop to it.”

Burch’s eyes became wide and owl-like in the dark. They walked in silence towards Cupola House, through the quiet streets where only occasional observers of the comet stood on their doorsteps quietly watching.

“If the mayor is behind it, then my pa did lie about seeing your ma start the fire,” said Burch eventually, his voice small and thin.

Nancy looked at her friend. “I’m sorry to say it, Burch. I think he must have done.”

Burch puffed out a long, slow breath, his eyes glued to the pavement as they walked. He stopped outside an inn, where the clink of glasses could be heard from an open window as the landlord cleared up. “At one time I’d have sworn on my life that Pa would not have done such a thing, but now I’m not so sure. It’s bewildering how his character has changed.”

“We must speak with him, see if he will tell us exactly what happened the night of the fire,” said Nancy.

“Yes, we must,” said Burch, his jaw clenched. “There’s something else, Nancy. I can’t stop thinking about the broken telescope in the town observatory. Why hasn’t the mayor had it repaired for the comet party tomorrow?”

A sudden memory tugged at Nancy’s brow. “When the mayor came into the haberdashery shop the day of Violet’s accident, didn’t he tell your father to go to the observatory to continue preparing for the party?”

“Yes, I think he might have done,” said Burch. “Why do you ask?”

“The observatory can’t be very big. Surely there are better suited rooms for the party preparations?” asked Nancy.

A muscle twitched in Burch’s cheek. “You’re right. Maybe that is a bit peculiar. Pa has a set of master keys to the Subscription Rooms. I’ll try and borrow them without him noticing so I can have a look around. If you can meet me at eight o’clock tomorrow morning outside the Rooms, we can find Pa and see what he has to say. We’ll try and look in the observatory too.”

With that decided, the children hurried on through the night. “Agatha told me of something else that could help free my mother,” said Nancy, going on to explain about the letter her aunt had spoken of.

“You must talk to Mr Greenstone as soon as you get back,” urged Burch, as they neared Cupola House.

“I will,” said Nancy, giving her friend a small smile. “I truly think we are a step closer to solving these mysteries, Burch. Tomorrow is going to be a better day for both of our families, I am certain of it.”

Violet was snoring gently when Nancy returned to the house and their grandfather was in his room, presumably asleep. Nancy’s limbs felt heavy with exhaustion, but her brain was as fizzy as a bottle of pop as she crept into the apothecary shop and stood in front of the herb drawers. A teaspoon of chamomile and lemon balm, a pinch of ginger. In the kitchen she ground the herbs and spice in a pestle and mortar, tied them up into a square of muslin cloth and made two mugs of fragrant tea. Quickly carrying the mugs upstairs, she placed them on the floor outside her grandfather’s bedroom and knocked on his door. “Grandfather, you need to wake up.”

The creak of bedsprings. “Nancy, it is very late, my dear. You should be in bed.” His voice was croaky, as if it needed oiling.

“I need to talk to you,” Nancy said urgently. “I know about my aunt, Agatha. I’ve seen her.” She gulped in a deep breath, the scented steam of the tea soothing her nerves as she waited for her grandfather to reply.

Footsteps across the room. The door creaked open a crack. Grandfather stood there in his nightshirt, his fingers shaking as he fumbled with his spectacles. “What do you mean, you’ve seen her?” he whispered in disbelief. “Is she all right? I’ve been so worried.”

“I think she’s all right. I’ve been to the prison,” Nancy said, suddenly feeling a little less brave.

“What!” Grandfather exclaimed; his cheeks creased in anguish. He stood back and ushered her inside.

Nancy picked up the mugs of tea and walked into his room, swallowing a gasp as she looked around. The warm glow of three oil lamps on the walls illuminated the heavy wooden furniture. Silver photograph frames of varying sizes dotted every surface: the bedside table, the mantel above the fireplace, the oak chest of drawers.

Nancy placed the mugs of tea on the bedside table, picked up a photograph and peered at it. A sepia image of two girls in long summer dresses and wide hats with gauzy ribbons. Their expressions were serious, but Nancy detected a glint in their eyes as if they were swallowing cheeky smiles. She placed it down and picked up another. Her grandfather beside the same two girls, older now, perhaps in their early twenties, standing outside Cupola House, next to a horse and cart with a board advertising Greenstone’s Apothecary Shop.

“These photographs are of Mother and Agatha,” whispered Nancy. Her grandfather had created a shrine to his two girls in his bedroom, a place where he could remember them in happier times.

Grandfather walked to his bed and sat on it with a heavy whump, the springs creaking in surprise. “How can you have seen Agatha at the prison? She is locked up,” he whispered, shaking his head.

Nancy returned the photograph to the table, took the mug of tea her grandfather was offering her and sipped it, the warmth easing some of her tension. She stood before him, speaking slowly and steadily of her visit to the police station with Burch, how they had learned that Burch’s father had witnessed her mother’s supposed crime, and finally, her unexpected visit to the prison and the encounter with Agatha.

Nancy’s grandfather placed his own mug of tea down with a bump, liquid sloshing over the side. “Prisons are dark and dangerous places; anything could have happened to you. All these years I have been trying to keep you safe and this happens!”

“But nothing happened. I am fine,” said Nancy. “Can’t you see? I had to try and contact Mother and do something to help.”

Grandfather rubbed his sallow cheeks, his eyes suddenly sorrowful. “I fear that I’ve failed you and Violet. With your mother gone too I felt hopeless, retreated into my shell like a mollusc. I should have been there for you and your sister.” He patted the crumpled sheets on his bed and Nancy placed the mug on the table and sat next to him. “I don’t approve of what you’ve done, but you have been very determined in trying to resolve matters,” he said, taking Nancy’s hand and giving it a light squeeze. A wave of tiredness and emotion at the day’s events spilled over her and she grasped his fingers, welcoming his warmth.

“Come here,” he said gruffly.

She nestled into his side, her shoulders relaxing a little.

“You remind me of your mother and your aunt; you have their grit and determination,” he said. “Tell me about Agatha. I’ve been so worried about her.”

“There was unrest at the prison because of the comet. The prisoners are all locked in their cells,” said Nancy, tilting her head to look up at him.

“Oh,” said Grandfather with a frown, pushing his spectacles onto his nose. “That explains it. Your mother and I tried to get word to Agatha…”

“You sent more handkerchiefs and messages to see if she was all right?” interrupted Nancy.

“Yes,” said Grandfather, looking a little bewildered at what Nancy had discovered. “But none of the usual people would help or even speak to us. I suppose that was because of the unrest.” He paused. “What else did Agatha say to you?”

“She told me she is married to the mayor. I saw a photograph through a window in the mayor’s house. It looked a little like Mother and the mayor standing in front of Cupola House, but now I know it was Agatha,” said Nancy. “Is the mayor the reason she is in prison? What happened?”

The crevices in Grandfather’s forehead deepened. “I had something the mayor wanted very badly, and I would not give it to him.”

He reached across and picked up the photograph of Nancy’s mother and Agatha standing outside Cupola House. He held the silver frame tightly, his eyes damp and overly bright. Nancy leaned in closer, waiting for him to reveal the truth she had been so desperate to discover.