The sea kept on coming, and the sound of the waves washing against the walls of the cave outside got louder. Soon I could smell the sea in the air. I looked at the green string, which had ended just as we reached the grotto. It lay on the sand beside my backpack, and I thought of the other end tied to the secret door under- neath the attic stairs.

    More than anything I wished I was at that end of the string. And then-- I saw it move. I didn't believe it. And then it moved again. Wanda saw it too. "Something's eating the string, " she whispered. "And soon it will come and eat us. " "Don't be silly, Wanda. How will it get through the portcullis?" "It probably set the portcullis trap in the first place, " said Wanda. "It will just press a button or something and--" "Stop it, Wanda!" I put my fingers in my ears. Suddenly there was a huge tug on the string, and it jumped underneath the portcullis. "Get it, get it!" yelled Wanda. I dived to grab it, but it was too late--the end was just out of reach. Wanda and I watched the green string move jerkily along the tunnel until it disappeared around the corner. "Now we'll never find our way home, " I mumbled, "even if we do get through the portcullis trap. " "Which we won't, " said Wanda. We could hear the sea getting even closer. There was a kind of swishing sound as the water gushed into the narrow cave outside and swirled around the rocks, and then a sucking sound as the water washed out again, and then another swishhhh . . . And then it happened. The sea poured in. It came in through the tiny gaps in the pile of rocks like water through a cheese grater. At first all it did was sink into the sand and disappear, but it was not long before there was a pool of water in the sand that didn't go away.

    And every time a wave threw itself against the rocks, more water poured in and the pool got deeper. The noise was horrible too. Now I knew how Brenda's cat, Pusskins, must have felt the day Aunt Tabby ran the rinse cycle while it was asleep in the washing machine. I decided I would never, ever laugh at Brenda's cat again. If I ever saw Brenda's cat again... The rinse cycle in the grotto just carried on. More and more water was coming in and, although Wanda and I were on the high bit of sand by the portcullis, we knew that it would not be long before the water reached us, too--and then kept going right up to that piece of seaweed way above our heads. Suddenly there was a massive thud against the rocks. A wave of water streamed in and splashed up at us.

    Wanda screamed and dropped the flashlight. It rolled down the sand toward the water. "Get it!" I yelled. "Quick!" We both dived after it. I crashed into Wanda and fell into the water. Wanda yelled and missed the flashlight, which rolled into the pool. Any other time I would have thought how pretty it looked. It lit up the water as it sank, and the whole grotto turned a bluey-green. We watched as the light dropped slowly down and came to rest on the sand at the bot- tom of the pool. And then it went out. And everything went black. Wanda grabbed hold of me so hard that it hurt. "It's dark, " she whispered. "I--I don't like the dark. "

    It wasn't the dark I minded; it was the water. But I didn't say that. I just said, "I-it's okay. I've got my key ring flashlight. " I pulled it out of my pocket and pressed the button. But it didn't work. It was wet. "Where's yours?" I asked Wanda. She fumbled through her pockets for ages, and then she said, "It's not here. I think I left it in the cave. . . . " "Never mind, " I said. "There must be some light getting in through the gaps in the rocks. Just wait until your eyes get used to it. " But our eyes didn't get used to it.

    It was horrible being in the dark. Really hor- rible. We couldn't see the water anymore, so we didn't know how fast it was coming up toward us, and I kept thinking we were about to get drowned.

    I opened my eyes so wide that they felt cold around the edges, but it made no difference. I could see nothing at all. It was completely, totally dark. Another rush of water poured between the rocks, and I felt the spray in my face as it splashed in. "At least Pusskins could see something, " I said to Wanda. "Aunt Tabby always leaves the light on in the laundry room. " "What are you talking about?" gasped Wanda. "Nothing, " I said. "Move back a bit, Wanda, my feet are in the water. " "I can't, " she said. "There's no room. I'm stuck right against the portcullis already. " "Well, start climbing it then, " I told her. "My feet are soaked. I hate having wet socks. "

    The portcullis was quite easy to climb, even in the dark. I hung the sword onto one of the bars and followed Wanda up until we both were as high as we could get. The metal was cold and sharp, but I didn't care. At least we were out of the water. But for how long? We didn't say much after that. The waves kept on pounding outside on the rocks, then pouring into the grotto. The water was right up to our knees and there was no way we could climb any higher when suddenly Wanda said, "A light! I can see a light in the tunnel. Look, look!" I nearly fell off the portcullis. Wanda was right. At the far end of the mushroom tunnel was a very faint greenish glow. And it was com- ing toward us.