Adventure! People talked about the idea as if it was something worthwhile, rather than a mess of bad food, no sleep, and strange people inexplicably trying to stick pointed objects in bits of you. -- Terry Pratchett, Interesting Times

Louise's boat was delivered two days later.

Ruth and Nancy had both stopped their redecorating efforts. They'd started spending most of their time outside, exploring the shore around the lake. Nancy got up early in the morning and prepared picnics. That way there was much less danger of being poisoned or having chandeliers dropped on their heads.

The lake was fairly popular with boaters. At least three sailboats could always be seen somewhere on the water. Motorboat engines rumbled in the distance. They even saw a few rowing boats and a canoe club.

"How will we ever stage an accident here?" Ruth grumbled, lowering her binoculars. She was sitting on the rocks just above the water's edge, watching a pair of motorboats racing each other to the harbour. "The first sign of a boat sinking and there'll be twenty people out to the rescue."

Nancy had her own pair of binoculars trained on the house. "Here comes Louise's boat now."

Ruth looked. She almost dropped her binoculars. "Good God! It's... It's purple!"

To be accurate, the top half — the part that would be visible above the water once it was off the delivery lorry and in the lake — was bright magenta. On its own that wouldn't have been so bad. Tasteless, but not terrible to an eyewatering degree. No, the worst part was the keel. The magenta paint had obviously been added by a previous owner. A strip of the boat's original white paint remained between the end of the magenta and the start of the blue paint on the bottom of the boat.

It looked like a toddler had been asked to decorate it.

"On second thoughts," Ruth said, "I don't think anyone will go to any trouble to stop that thing sinking."

~~~~

They didn't dare go near the boat until Louise had taken the car and gone into town. Even when she was safely out of sight, they approached the dock warily in case she'd rigged the boat to explode.

It was even uglier up close. The magenta paint had been applied unevenly. Hints of the original white colour showed through.

Ruth climbed onto the deck. Thank god, the boat wasn't quite so ugly from here. It had a narrow walkway around the sides of the cabin, which widened into a larger triangle-shaped area at the front. Indoors, one wall of the cabin was taken up by a large sofa. The other wall was a row of cabinets beneath the windows. A small table was placed close to the sofa, allowing people to squeeze past to the steering wheel — or whatever it was called on a boat.

By boat standards, it was probably very comfortable. Ruth looked at it more as a potential murder weapon, and was very disappointed. How could she drill a hole in the floor all the way through the hull? It would be obvious at once!

Some thought was required.

~~~~

Ruth thought for the rest of the day. She drew complicated plans of how she could cut a plank out of the hull and let the boat slowly fill with water. Then she threw them in the fire.

Louise went out to the boat as soon as she got back. Strange hammering and thumping noises issued from inside.

Was it possible? Was Louise going to very helpfully sink the boat herself? More importantly, would she have the good sense to sink herself with it?

It was evening before Louise returned to the house. She looked quite sickeningly pleased with herself. Ruth and Nancy tensed when she headed into the kitchen.

The TV continued playing in the background while they craned their necks over the sofa. Louise was moving around somewhere near the fridge. Her footsteps came towards them. Their heads immediately snapped back round. When she walked into the sitting room she found them transfixed by Laurel and Hardy.

"Make yourselves supper tonight, girls!" Louise said, scattering exclamation marks like confetti. "I'm going down to the boat! I won't be back until late! Tell Stevie not to sit up for me! Goodnight!"

She swept out of the house before either girl could think of anything to say.

"Stevie," Ruth repeated in disgust. She and Nancy shuddered.

~~~~

Nancy sat at her window well into the night. She kept her binoculars clapped to her eyes. Something was happening down on the boat. Occasional flashes of light shot out of the windows. They immediately disappeared.

She fell asleep before Louise came back.

~~~~

In spite of her late night, Nancy was awake well before the others. She made tea and poured out cereal for everyone. It was the perfect opportunity to tamper with the food. That was exactly why she didn't.

Ruth came down next. She eyed the bowls and teacups suspiciously.

"You know," she remarked, "sometimes I wonder if I can trust anyone. Even you."

Nancy said practically, "Don't be silly. I'd never be able to plan a murder without you."

Ruth slowly nodded. She didn't take her eyes off Nancy as she poured out her tea. "What about afterwards?"

"Then I'll need you to help cover it up, won't I?"

They stared at each other like two cats circling round the same mousehole.

This amiable situation lasted until Stephen staggered into the kitchen, yawning fit to dislocate his jaw.

"Morning," he mumbled. It sounded more like 'Murng'.

He spooned instant coffee into a mug, poured in water, and drank it in one go. He looked slightly more awake afterwards. "Louise wants me to go out in that boat of hers. Do you think it's safe?"

Ruth and Nancy exchanged looks. Ruth raised an eyebrow. Nancy raised one. Ruth raised her other one. So did Nancy. In this way they silently discussed the situation and reached the same conclusion.

"As safe as staying indoors," Nancy said truthfully.

It was really quite generous of Louise to spare them the trouble of killing their own father. If they were especially lucky, and she was especially incompetent, she'd accidentally drown herself too.

Louise chose that moment to bound into the kitchen. She was grinning from ear to ear. Anyone with brains would have been suspicious at once.

"Your father and I are going for a sail," she said. "Do you want to come?"

Ruth smiled sweetly. "Sorry. I get seasick when I wade through puddles."

"And I have to—" Nancy searched for something suitably urgent that she had to do. "Go to the hairdresser. I want to have my hair curled."

Louise's face fell. "Oh well. There's always tomorrow."

She took a bowl of cereal and went into the sitting room. They heard her pull the curtains open. A outburst of swearing followed. It was enough to turn the air blue.

Stephen dropped his coffee cup. "She's having a stroke!"

He hurtled out of the room at a speed that would put many athletes to shame. Ruth and Nancy followed more sedately.

His idea, unfortunately for them, was wrong. Louise was standing in the middle of the room, the picture of health except for her bright red face, shaking a fist at something outside the window. When she saw Stephen she calmed down enough to use printable words.

"The boat! It's gone!"

Everyone crowded around the window. From here they had an excellent view of the jetty. There was plenty to see. Someone was hanging her laundry from a dinghy's mast. Two children were playing hopscotch on a yacht's roof. Someone else was having a disagreement with someone on the pier. There was one thing they couldn't see: a hideous magenta boat.

"Someone's stolen it?" Nancy asked incredulously.

Either a public-spirited individual had taken it off somewhere to repaint it, or the world's stupidest thief had chosen the most distinctive boat they could find.

Louise pulled a face. She pointed. "It's sunk."

Nancy followed the line of her finger. She saw it. The cabin's windows and roof were all that was still above the water.

"What happened?" Stephen asked.

Nancy thought of the time Louise spent on the boat last night. She remembered the strange sounds and lights. She remembered Louise's disappointment that Ruth and Nancy weren't going on her planned boat trip.

"The salesman sold me a damaged boat!" Louise wailed.

Nancy and Ruth communicated through raised eyebrows again. Both of them thought the same: not only had Louise tried to kill their father, she had failed spectacularly at it.

~~~~

Louise's next efforts were equally underwhelming. The bowling ball perched on the landing had the advantage of being funny. Stephen's baffled expression when it crashed down, missing him by several feet, had been even funnier. The attempted electrocution-by-toaster was just pathetic. It did nothing but turn a perfectly good slice of bread into a pile of ash. Ruth, who had been the lucky person to set off the toaster, hadn't even got a mild shock.

Ruth and Nancy began to spend more and more time at their original house. According to their cover story, they were getting it ready for the estate agents. In reality it was much safer than being in the same house as Louise.

And of course it was easier to plan a murder without worrying about being overheard.

"I've got it," Nancy said, closing the book of household poisons.

Ruth was practicing archery in the garden — with rubber arrows so the neighbours wouldn't get suspicious. She loosed an arrow before answering. "Arsenic or cyanide?"

"Neither. Pennyroyal oil."

The arrow landed a foot away from the target. Ruth stared at it, dejected. Her idea of an archery accident was going to take more work than she'd expected. She dropped the bow and joined Nancy on the kitchen steps.

"What exactly is pennyroyal oil?" she asked.

Nancy was scribbling something in her diary. The word 'mint' showed up repeatedly. Odd; she'd never liked mint before. She put the diary aside and opened the poison book again.

"Listen. 'Mentha pulegium, also known as pennyroyal or pennyrile, is a plant in the mint family. It's found—' Never mind." Nancy saw Ruth's impatient expression and skipped ahead. "Here's the important parts. 'It is used as an insecticide and pest repellent. Sometimes it's used as a cooking herb. Its leaves were used to treat smallpox and tuberculosis.'"

"If it's a medicine it's no use to us," Ruth interrupted.

"Wait! You haven't heard the rest. 'It can be used to make herbal teas. However, it is poisonous in large quantities. Its oil is especially toxic. The poison's effects depend on the amount ingested. A small dose of pennyroyal oil causes nausea, vomiting and dizziness. Larger doses cause seizures, multiple organ failure, and often death. The plant contains pulegone, which damages the liver and kidneys. There is no antidote to pennyroyal oil poisoning.'" Nancy looked up triumphantly. "It smells like mint, so they won't notice anything if we put it in their desserts."

Ruth took the book away from her. She read the entry over to herself. "All right, it's the most promising one we've seen so far. Where do we buy it?"

Nancy looked shocked. "We can't just go out and buy poison at the drop of a hat! We need to prepare first! We need to become health food fanatics with a bizarre fondness for mint. Then Louise won't be suspicious when her food smells of the stuff."

Ruth could see the flaw in this plan from a mile away. "She'll be even more suspicious if we become, how did you put it? health food fanatics out of nowhere."

Nancy grinned. "That's why her poisoning attempts will come in handy. She's still trying them. Usually in the bread, for some reason. We'll just make sure she sees us eat her bread. Then we'll complain we feel sick. Then we'll pretend we want to build up our immune systems..."

"All right, I get the picture."

Ruth picked up the bow and arrows again. Any plan that required intentional self-poisoning as a first step was too complicated for her. It was time to consider the archery accident again.

~~~~

It was no wonder Louise usually put poison in her bread. The stuff was always stale, even when just out of the oven, and so tough that you needed a saw to cut it. The poison probably improved the flavour.

Ruth looked at the slice on her plate. She steeled herself. She took a bite.

Nancy did the same on the other side of the table.

A minute later both women ran for the sink.