Mrs.Carter, startled, raised herself, and at that same moment Henry gave a cry, a weak little trembling sound.
She turned and saw the boy; as their eyes met he felt the Terror rushing upon him.

He flung a last desperate appeal for help, staring at her as though his eyes would never let her go, and she, finding him so unexpectedly, could only gape.

In their silent gaze at one another, in the glassy stare of Mrs.Carter and the trembling, flickering one of Henry there was more than any ordinary challenge could have conveyed.
Mrs.Carter must have felt at the first immediate confrontation of the strange little figure that her feet were on the very edge of some most desperate precipice.

The long room and the passages beyond must have quivered.

At that very first moment, with some stir, some hinted approach, Henry called, with the desperate summoning of all his ghostly world, upon his gods.