He was dangling in space, the hard pavement thirty feet below him, with no possible way of pulling himself up to the roof again.

And the hook was so small that there was no place for his other hand.

The only way he could cling to it at all was to grasp his wrist with the free hand as a partial relief from the strain upon his arm.
"Hold fast!" called Patsy.

"I'm coming." She sprang up the steps, through the boy's room and into the hallway.
There she quickly perceived the ladder, and mounted it to the roof.
Taking in the situation at a glance she ran with steady steps down the sloping roof to where the plank lay, and stepped out upon it far enough to see the boy dangling beside her.

Then she decided instantly what to do.
"Hang on!" she called, and returning to the roof dragged the end of the plank to a position directly over the hook.