Beryl Austen and Effie Hargreaves slept in a room almost opposite to Lindsay's and Cicely's. Before eight o'clock arrived the two latter contrived to make an excuse to go upstairs, and hastily completed their preparations. The arrangements were ingenious. They fastened their rat very lightly by two pieces of thin sewing cotton to the middle of the piece of tapestry that formed the roof of the great four-post bed. To the cotton was attached a long strand of string, which passed through the curtains and out at the door (conveniently near the bed), the end being hidden under the mat on the landing.
"You'll see, when we jerk the string, the cotton will break, then down will plump the rat right on to their chests," said Lindsay, justly proud of her inventive powers. "Poke the box under the valance, Cicely, quick! I thought I heard someone coming."
The cardboard box contained a bobbin, to which a second string was tied, and concealed in the same manner as the first.
"I don't believe they'll suspect anything," said Cicely. "Won't it be lovely to give them a scare!"
At bedtime the conspirators retired innocently as usual, having wished Beryl and Effie good night in the passage.
"I nearly said I hoped nothing would disturb them," laughed Lindsay, "but I thought it would be wiser not. How long must we leave them to go to sleep?"
"About half an hour, I should think. Let us get up as soon as we hear the clock in the picture gallery striking nine."
The twilight lasted long, so it was still quite possible to distinguish objects as two nightgowned, barefooted figures stole gently across the landing. Fortunately everything was perfectly quiet in the upper portion of the house. The younger girls were in bed, and the elder ones were with the teachers downstairs.
"We must be sure to work the right strings," breathed Lindsay. "Have you got yours? This was mine, with a knot at the end."
She gave a smart pull, and the bobbin rattled loudly inside the box. They could hear it plainly, even through the closed door.