In summer the sun doesn't set as soon, and the nights are very short. It gives me time. I can avoid the moon for the longest then, and I do not have to put as much effort into hiding, waiting for the moon to come. I like the summer for that reason. Which brings me neatly to why, yesterday evening, when everyone else as asleep (except James and Sirius, who by now I have come to the conclusion that they just don't sleep – and how they manage it baffles me), I was lying tucked into the duvet with parchment on my pillow, drawing onto it with my wand.

It was about nine/ten o'clock, I think, and the sun was still up. I was planning out the map that we'd decided on. The parchment I was drawing on was to be our Marauder's Map. James thought of the name. He'd said it had a certain drama to it. I can rather see his point. However Hogwarts is a big place, and if you want to cover every room, staircase and secret passage on one piece of parchment, it was going to be hard work. But no matter how willing I was to stay up here and work on this map, I couldn't. It was the night of the full moon, and even though nights like that never ran smoothly, it was even less so yesterday.

It was almost an omen that I had fallen asleep. I'm usually never relaxed on the night of the full moon to sleep. I'm usually waiting for the only boy in our dormitory who does not know my secret to fall asleep himself and then I would make my way down into the grounds (with James, Sirius and Peter following at a safe distance beneath James' invisibility cloak) and make my way to the Shrieking Shack. Yet somehow, yesterday I had fallen asleep. I don't remember falling asleep myself, but I do remember James shaking me awake in the red light of dusk.

"Pst, Moony. You awake?" I woke up feeling surprised and glanced at the watch I had fastened around my wrist. It was getting dangerously close to sunset. How could I have slept? I sat up. Sirius was rooting through James' trunk, searching for the invisibility cloak and Peter was sitting cross-legged on his bed, watching me with distinct nervousness. Still drowsy, I got up as Sirius pulled the cloak out from under some of James' books, earning a wince from Peter as a pile of transfiguration books toppled with a loud clatter. My eyes darted immediately to the only other occupied bed, but there was no movement at all.

"Sorry," whispered Sirius, swishing the cloak around and bringing it out to its full size. Peter slipped off the bed and scurried over to Sirius as he disappeared under the cloak. I crossed to the door and took one last look behind me. James had crouched down and picked up a rat from the floor. Peter had already transformed: Sirius' suggestion as it saved room under the cloak. Sirius' head appeared out of thin air, indicating where he was. James looked over at me.

"Right behind you," he whispered, and he walked over to where Sirius was. Both disappeared as they vanished under the cloak. I opened the dormitory door and descended the stairs quietly.

The common room was empty. Good. With a quick word behind me to check that the others were still there and I crossed to the portrait hole and climbed out. I always took a long time to climb out and close the portrait behind me. I was aware of the others needing to get out without being noticed by the Fat Lady. I went ahead as usual. I was the only student in the castle allowed to be out at this time. I would meet with Madam Pomfrey and go down to where the Whomping Willow was planted; then through the secret passage to the House and wait for the moon. It always felt better now, because of what the others had done to help me.

Moony, Wormtail, Padfoot and Prongs: best friends. It made me feel better now that they were there with me. No one else was allowed to know though. Madam Pomfrey took me down to the Willow and helped me down into the hole where I would walk along the passage to the House and wait for the others, or the moon, whichever came first.

I watched the sleeping town of Hogsmead through the crack in the window boards. Although the sun had now set, the moon had not yet risen, but it still unnerved me. I knew what was coming and it would be painful, as always. Suddenly I heard a voice behind me in the passage. It was James. Why was he not in animal form? Something was wrong. I strained my ears to try and hear what he was staying.

"Stay here. I'll go." Then the sound of hooves retreated down the passage. What was going on? A rat scurried past me and sat on the windowsill: Peter.

"Wormtail?" He nodded. "What's happening?" Sirius appeared out of the air behind me, looking worried.

"He's not happy with me," he said.

"Who?" I asked.

"Prongs."

"Why? What did you do?"

"I might have said to Snivelus how to get in here."

"YOU DID WHAT?" Sirius looked taken aback again.

"It was a joke," he said, defensively.

"You told him, knowing full well what he'd do, how to get into the passage; the passage, moreover where there is likely to be a werewolf any second now?"

"I thought it would be funny."

"It could kill him, or worse. Sirius..." My using his forename seemed to give some depth to the situation. He now looked very afraid. Right on cue, the moon slid out from behind a cloud, and the room was bathed in moonlight. Sirius quickly transformed. The dog now barred my way down the passage. He was buying time. He needed it. Peter scurried under the bed, watching with his beady eyes. The burning sensation of my own transformation started in my head as spread quickly. I could no longer control my actions. If Snape made it into the tunnel I would have to rely on the others to keep him safe now.