"So Jamie, where do we start?"
"The kitchens," James said determined. "We can interrogate the house-elves."
"Alright, to the kitchens then. But let's pick up the cloak first. It might come handy."
Twenty minutes later, the portrait guarding the entrance to the kitchens spookily moved aside.
"My dearest house-elves," James declared, as soon as the two pranksters had appeared out of nothing. "I would like to require your cooperation in our investigation. We are bound to find the disturber of the peace in this beautiful castle. Do you agree on helping us?"
The house-elves just stared at him blankly.
"He wants you to answer some questions," Sirius said with a smirk, and immediately the house-elves began to smile.
"How can I help good sir? I is wanting to answer any question," one of them said.
"Well, recently some students ended up in the hospital wing due to poisoning. It turned out the fried eggs held a mild poison. So we would like to know who entered the kitchens on the evening of the day before yesterday," James explained.
"I has not seen anyone, sir," the house-elf said.
"Bu' tha' im'ible," Sirius mumbled with his mouth stuffed with grub the house-elves had offered him.
"Sirius is right, that's impossible. Someone must have entered to poison the eggs."
"I has not seen any student enter the kitchens," the house-elf said.
"Was it a teacher then? Or a house-elf?"
"A teacher has not entered either. House-elves I does not know. I sees them all the time."
"Alright, thank you anyway. Sirius, stop eating now. We need to think this over," James said while pulling Sirius out of the kitchens and back towards the Gryffindor Tower.
"Aye, James Sherlock Holmes!"
"Who's that?"
"Oh, just a Muggle detective I read a book about once."
"But what do you think about our current research?"
"I think someone used a house-elf to get the poison in the food."
"Sirius, I've been thinking exactly the same thing."
"Now we only need to find out who it was."
"We ask the portraits in the corridor leading towards the kitchens."
"Brilliant idea, James. It even could have been one of my ideas!" Sirius said, and James punched him.
"As if you could ever come up with such a bright idea," he muttered in such a way Sirius could still hear him.
And slapping each other, they returned to the kitchens.
"Sir? Sir Cadogan? Are you there?"
James and Sirius were standing in front of a painting that was to be found in the same corridor as the painting of the fruit bowl that marked the entrance to the kitchens.
A small knight was sleeping next to his pony. As they called him, Sir Cadogan stood upright.
"Boys? What are you doing here? Why did you disturb my beauty sleep?" he asked with a high pitched voice.
Sirius and James looked at each other with amused expressions.
"We're terribly sorry, Sir, we didn't mean to. But since you're awake now anyway, could you tell us who went through this corridor two days ago?" Sirius said.
Sir Cadogan's eyes grew big. "You want me to remember every person who passed through this corridor? While the Hufflepuf Common Room is only meters away? Are you insane? It would take years to tell you. I would get wrinkles! Oh no, wrinkles!" He sank down on the grass of his painting and buried his head in his hands. "Wrinkles, no! No wrinkles!" he muttered sobbing.
Sirius had to do everything he could to stuff his laughter.
"Sir, can you tell us which non-Hufflepuffs took this way? It won't take that long, so you won't get wrinkles," James tried.
Sir Cadogan was still sobbing. "I… I saw a… Slytherin and a Gr… Gryffindor. That's all."
"The Slytherin, what did he look like?" Sirius asked. "Did he have greasy hair?"
"No, she had black hair and it was not greasy at all. She was… she was…" he trailed off while a dreamy gaze appeared in his eyes.
"Now we're stuck with a silly portrait that's in love with a Slytherin girl with black hair that poisons students. Great, absolutely spiffing," James said sarcastically.
"Thank you, Sir Cadogan, we'll go now," Sirius said, but Cadogan didn't even hear him and they exited the corridor.
"It must have been the Slytherin!" James said.
"Slytherins, beware! Poisoner, show yourself if you dare," Sirius suddenly shouted.
"Sirius, please stop speaking in rhymes."
"If not, we'll cut off your hair."
"You make a horrible poet, do you know that?"
"If, as we thought, you turn out to be Snape, we will not let you make another escape. We'll hold on to your filthy cape, until you confess you did it like… like… like a grape!"
"A grape? Siriusly?"
Sirius grinned, for he knew James said Sirius' favourite word on purpose.
Then, a marvelled expression crossed Sirius' face.
"I do know who did it," Sirius said and James looked at him surprised.
"Snape? His hair is long enough to mistake him for a girl," James offered.
"No, I think it was my dearest cousin."
"Wait, you mean Bellatrix?"
"She's evil enough to poison students and – although I hate to admit it – smart enough to figure out how to enter the kitchens."
"She's a Slytherin with black hair and she can have used a charm to discompose Sir Cadogan," James continued.
"Let's arrest her!" Sirius said, a smile stretching out on his face.
"Right away, Sirius!"
But suddenly they heard a cold voice behind them. "That's enough for now, boys."