Then she started down the front walk toward the lilac bushes, though she did not know the boys were there.
"She's comin' after us," whispered Ted.

"Come on, Bob." Bob was aware of the danger of getting caught.

He prepared to run.
Now there is this advantage to a tic-tac.

Once you want to escape you can take it with you by the simple process of pulling on the long string, when the pin is jerked from the window-frame, and you can drag the nail and all with you, thus leaving no evidence behind.

This was what Bob did.
Quickly winding up the string as he pulled the pin and nail toward him, he and Ted started to run, crouching down low so as not to be seen.