“Nobody touch anything,” Tempest commanded. “Look around for more clues, but don’t touch anything until we know more.” She spun slowly and surveyed the room. “Gideon, take the walls and windows. Ivy, look at the books on the bookcase devoted to Arthur Conan Doyle and Agatha Christie. Kira, take the children’s literature bookshelf.”

“Kid lit,” said Kira. “Got it.”

“Cameron, take the bookcase with nonfiction, foreign translations, and short story collections. Mrs. Hudson, please look at the remaining bookcase of general alphabetized classic authors. I’ll take the other furniture. I’ll see if I can unlock that door.”

Everyone got to work on their respective tasks. Everyone, that is, except for Ivy.

“Why are you doing this?” she asked Mrs. Hudson.

“Me? You’re the ones who lured me over here!”

“Someone asked you to come over?” Tempest asked.

“Well, no. But you were all coming back over to the house tonight again, after whatever nonsense went on last night that you weren’t telling me. Of course I’d be curious. How could I not be?”

“Can we stop arguing?” Gideon said. “Mrs. Hudson, do you have your cell phone?”

For three seconds, everyone simply stared at one another. Then there was a collective round of groans.

Mrs. Hudson reddened. “I should have thought of that.”

“You really should have,” Cameron muttered.

“I was in shock,” she snapped, then looked flustered as she rummaged through her purse. “Where did it go?” Frantic, she dumped the contents onto the rosewood desk. Out poured a hardback notebook, two blue ballpoint pens, a pencil that was nearly a nub, lipstick in the shade she was wearing, a bulging wallet, a jumble of keys with a copper M on the keychain, a mini first aid kit, and two rumpled bookmarks.

But no cell phone.

“I swear it was in my purse.” She shook the empty bag, growing more frustrated by the moment.

“May I?” Cameron took the purse from her hands and looked inside it himself. He shook his head. “Nothing is hiding in here.”

Ivy took it from him and peered inside. “Not even lint. This is the cleanest purse I’ve ever seen. Like she knew someone would be looking at it.”

“What are you saying?” Mrs. Hudson straightened her shoulders as she faced Ivy.

“Obviously,” said Cameron, “we’re implying that you’re the person who trapped us in here. You’ve had it in for this library since the start.”

“It would have been less suspicious if you’d simply said you didn’t bring your phone with you,” Ivy added.

Mrs. Hudson narrowed her eyes at Ivy. “I came over to snoop and try to gather information to get more townspeople to see my point of view that you shouldn’t be allowed to open a library here. You really think I’d leave my cell phone— my only camera —at home?”

“You admit you were snooping to try to ruin the library!” Cameron was nearly shouting now.

“Of course. You lot are up to no good.”

“Elderly people often leave their phones at home,” said Cameron. “It would have been completely believable.”

“Well, it’s a good thing there aren’t any elderly people here. I’m sixty-three. If you’re calling me elderly and questioning my competence, there really will be a dead body here in a minute. It wasn’t me, so you’re all wasting your time thinking so. We need to figure out how to get out of here. Gideon is the only one paying attention to something sensible.”

Gideon gave a start and looked up from the wall where he was kneeling. “This wall has been damaged at the baseboard, like a crowbar was wedged in to pry it up. But it’s not an opening we can get out of. Just pointless destruction.”

“Another one,” Tempest murmured.

“ Another? ” Kira asked.

“There’ve been a bunch of weird things damaged as we finished this first round of interior renovations,” Ivy said.

“That’s not important right now,” said Tempest. “We need to figure out how to get out—”

“I’d say it’s a very important clue,” said Mrs. Hudson. “Because this is a game, isn’t it? And Harold loves games.”

“Tons of people love games,” said Cameron. “ Living people. Harold isn’t playing this game.”

“Apparently,” said Mrs. Hudson, “I was being overly generous in my estimation of your intelligence.”

“Generous?” Cameron’s face reddened. “How you’ve treated me these past few months is what you’d consider generous?”

“I was upset at Harold,” Mrs. Hudson said. “Not you. I thought you’d have the backbone to make your own decisions about the library.”

“We all love the idea of a library,” said Kira. “So if you’re going to be upset at Harold and Cameron, you need to be upset at all of—”

“Fighting is counterproductive,” Tempest interrupted. “Let’s figure out how to get out of here. Then everyone can go back to arguing about whatever you want to.”

She didn’t need a mutiny on her hands. It was difficult enough to think while trapped in a room that was possibly filled with poison. She didn’t need them all turning on one another.

Kira knelt at the spot on the wall where Gideon had noticed the damage. “You sure there’s not a secret passageway through here?”

“There were no secret passageways in these old houses when they were built,” Mrs. Hudson said. “But I wonder…”

“No secret passageways,” Tempest said. She’d seen her dad and Victor, their architect, working on the house plans, so she knew there weren’t any secret passageways. But standing inside the fairy-tale house, it certainly felt as if anything was possible. “The walls are solid, but not thick enough for any secret passageways. And before you ask, I know that because we did an inspection when we surveyed the house for the renovation. The spot is a dead end.”

She looked around. Something felt different about the room from when she’d been there yesterday, but she couldn’t place it.

The room was sensory overload, so it was hard to think. Handmade bookcases both lined this room that had once been the largest bedroom of the house and were also placed to form two rows. Once the library was approved, they’d be knocking down a non-load-bearing wall to make one larger library room, so this room only had a portion of the books that would be there when the library opened.

Agatha Christie had a whole bookcase devoted to her fiction, plus nonfiction written about her. The other bookcase sections were divided into books for kids, English translations of classic mystery fiction from around the world, early detective fiction from Edgar Allan Poe and Wilkie Collins, golden age mysteries of the 1920s and ’30s, and nonfiction books about crime fiction and poisons. Once the room was converted, it would also include Sherlock Holmes originals and pastiches, anthologies and mystery magazines, Penguin classics, and the noir and hard-boiled books that were currently downstairs, as well as several other sections they hadn’t yet figured out. Downstairs would have popular books for casual browsers, but this floor was for the serious mystery fiction fans.

Tempest scanned the shelves once more, her feeling of unease growing with every passing moment.

“This is ridiculous,” Kira said. “Why couldn’t I have gone to a café to read before it was time to come over? Oh!”

“You thought of a way out?” Cameron asked.

“Even better,” said Kira. “I have no idea what time it is without my phone, but Milton will be arriving in a little while.”

“So will Sanjay,” Tempest said, “but that doesn’t help us.”

“Sure it does,” Kira insisted. “They’ll have their cell phones.”

“But we can’t risk breaking the window to lean out and ask them to call for help.”

Kira’s face fell.

“I know what’s wrong.” Tempest looked around frantically. She didn’t see Ivy.

“Um, just about everything?” Gideon asked.

“Ivy?” Tempest called.

Her friend had vanished.

“Ivy!” Cameron repeated, whipping his head around.

Ivy poked her head out from behind the Agatha Christie bookcase. “Sorry. Didn’t mean to worry you. I got distracted because I found another clue.” She held up a folded sheet of paper.

Mrs. Hudson was at her side in a heartbeat, taking the paper from Ivy’s hands with a tissue. She carried it to the desk and unfolded it with a tissue in each hand.

“The whole room can’t be poisoned,” Ivy said with wide eyes. “Can it?”

“Can’t be too careful,” said Mrs. Hudson.

“ Beware the crooked house ,” Ivy read from the paper. The handwriting was the same block lettering. “ You must get out by 4:50. How will you depart? ”

“This trickster can’t decide if they like rhymes or riddles,” Kira said.

“And this house isn’t actually crooked,” Gideon said.

“It sure looks like it is, though,” said Kira. “With its fairy-tale wobbly roof. This clue is useless, since the whole house is crooked.”

Gideon shook his head. “The architecture is high-quality, and the structure is solid. Even the floors are level after a century. I wonder if the clue means something else besides the house.”

“Gideon is right,” said Ivy. “ Crooked House is an Agatha Christie book.” She ran to the shelf of Agatha Christie novels.

“Remember not to touch anything!” Cameron called after her. But it was too late.

“Ah!” Ivy cried out, dropping the book as if it were a hot coal.

Blood bloomed on her hand.

“Poison,” Ivy whispered, her eyes wide with horror. “I’ve been poisoned.”

Even if they’d be able to shout loudly enough for Milton and Sanjay to hear them once they arrived, Tempest was certain of one thing: they no longer had time .