If he remembered it so clearly, of course his father would remember it too.

There was the point of danger.
The moment that he had come round the corner of the building he found that his surmise had been correct.

An electric lamp burned in the laboratory, and the silver squares of the three large windows stood out clear and bright in the darkness.

The centre one had been thrown open, and, even as he gazed, Robert saw a dark monkey-like figure spring up on to the sill, and vanish into the room beyond.

For a moment only it outlined itself against the brilliant light beyond, but in that moment Robert had space to see that it was indeed his father.