For the next week the gang scoured the library for ideas on potions and charms. Making lists and narrowing them down to suitable ones they might be able to use. Of course they all did their homework aswell, but found it hard to concentrate, as the prank they were planning played too heavily on their minds. It never occurred to them to tell a teacher, for a start they would never tell tales on a student, even a Slytherin and secondly they would have to reveal how they found out something they could not do.

They were all sitting in the library on a wet thursday afternoon, Sirius had already got bored of reading and was practising balancing his wand on the end of his finger, with Peter as his captive audience. Remus and James were sitting side by side, leafing through old charm spell books, giggling every now and again as they found out something that amused them, then sharing it with the group.

Lily was pretty much oblivious to all this, she was so absorbed reading her book. It was an old potions book, obviously little read, because it was so dusty it made her sneeze when she opened it. As she was flicking through, she came across something that caught her eye.

"Hmm, 'polyjuice potion', changes the drinker into whomever they want for an hour, as long as they have a part of their body,s uch as blood or hair" Lily read outloud to herself, musing it over, thoughtfully. James overheard her

"Lily! That's it! What could be more perfect, all we have to do is get Rodolphus out of the way for a while, then we can pretend to be him and some of his gang! Think of the chaos we could cause!" James had jumped up from his chair, in his excitement and enthusiasm

"Shh! Calm down Prongs! We don't want everyone knowing about it do we!" Remus whispered, pulling James back down into his seat

"What does this potion involve and how soon can we have it?" Sirius asked looking at Lily, suddenly interested

"Well it is a very difficult potion to produce and must be made very precisely for it to work." Lily said curbing their enthusiasm somewhat "It says here it takes a month to brew as well!

"A month! I didn't want to wait that long! But then again he'll be expecting us to get him straight away won't he? So he'll be on his guard. Well, we'll just play it cool, for a while and let him bask in the glory, then hit him with the best prank ever!" James said, picking up his enthusiasm again. He began to rub his hands with glee, "Oooh we'll get him so good, people will always remember it, they'll still be talking about it long after we've gone!"

"Trouble is.. none of us here is any great shakes with potions, even though you're taking it James!" Remus cautioned, "Do we know anyone who we can trust, who could do it for us?"

James immediately looked at Lily "She's brilliant, she outshines everyone in the class, she could do it easily!" he said proudly

"I'm not as good as Severus, but I suppose I'm not bad" Lily said humbly, "Of course I'll do it, I want to get Rodolphus back as much as, you all do!"

"Lily Evans! We'll make a Marauder out of you yet!" Sirius joked, pretending to be shocked

"Lily blushed and looked down smiling, then looked up at James who reached over the desk to kiss her tenderly in thanks

"Well all we need to do next is find out what the ingredients are" Remus stated, looking over at the book thoughtfully

"That's the difficult part, some of the ingredients listed are not generally available to students, we'd have to ask our Potions teacher for them!" Lily said, looking around at the gang, knowing this statement would be met with disdain

"Not if we can get into his office and take them without him knowing!" James said with an impish glint in his eye

"How? He's always hanging around his office and he's puts a good locking charm on the door too!" Lily stated

"Oh, we have ways!" James replied giving her a wink and touching his nose. He hadn't told her about the invisibility cloak yet.

They planned to use a distraction, to get their old potions professor out of his office quickly, so he didn't have the chance to lock it. Then one of them could sneak in unseen under the cloak and take whatever they needed, filling up the various bottles and jars, he took from with water to keep their levels the same so no-one could tell they had been tampered with.

They put their plan into action at the weekend, deciding it would be easier as Professor Cobalt was always in his office on a Saturday night, as he preferred to be alone rather than socialising with the other teachers. After memorising the list Lily had given him, James made his way down to the Slytherin dorm with Sirius, Remus and Peter, already wearing his cloak. He was to be the one to go into the office to collect the potions, while his friends caused a disturbance outside.

It would be easy; James waited in his invisibility cloak, while the others stood hanging around in the corridor for the next Slytherin to come along to pick a fight with. Sirius was the one who was going to find this the easiest, being a natural actor, Remus and Peter finding it a little against their nature.

As soon as a group of boys came along, Sirius stood out in the corridor and stuck out his leg, tripping up one of them. After a few sharp words a fight ensued with lots of pushing and shouting. Professor Cobalt soon appeared at the doorway of his office, a face like thunder. He marched up to the group and began pulling the boys apart. Sirius was to keep him out of his office as long as he could while James sneaked in unseen. He nervously searched around not knowing were to look first, trying not to knock anything over, but he soon found what he was looking for.

Once he had collected all of the ingredients he gave the signal of a thumbs up, with just his thumb showing from under his cloak. Peter who was looking out for this signal, nodded to the other two and suddenly everything quietened down again.

"Sorry about that Sir, it was just a misunderstanding" Sirius said apologetically, trying his best not to smile. He had enjoyed that little subterfuge

"I want him punished! He tripped me deliberately! Why would a Gryffendor just happen to be hanging around down here and just happen to have his leg in the wrong place and not notice!" The boy Sirius had tripped said,repeating Sirius's excuse.

"Qiute right!" Professor Cobalt agreed, "30 points from Gryffendor! Now can you all please go back to your dorms where you belong, I want try to enjoy the rest of my evening..in peace and quiet!" He emphasised the last words loudly and with that he disappeared into his office slamming the door behind him. As the Slytherin boys walked away glowering, the gang couldn't help sniggering, they had just managed to pull off thier plan and felt pretty good about it.

Once back in the gang's dorm room, James unloaded the potion ingedients out of the box he had been carrying them in, to show Lily. She studied the vials carefully and checked them off against the list in the book

"Well, I suppose I had better get started" she said getting up and picking up the book and box of vials.

"But it's a Saturday night! Don't you want to relax?" James protested

"You want this potion as soon as possible don't you?" Lily said in return, "I've got to find somewhere private to brew it yet! I think that old unused classroom on the way to Divination would be a good place"

They all agreed and Lily began to walk down the stairs.

"Wait Lily! I'll come with you!" James shouted after her

In the end, they all ended up going with her

Once they found the classroom she set up her cauldron and lit the magical fire ready, hoping that James's faith in her abilities wasn't unfounded.