This acts as an insurance against driving protest below the surface where it may take on more sinister forms.

As he stared at them, they seemed to form strange and sinister forms in the air.

A head and shoulders appeared from the stairs; then the body of a man - a crouching, sinister form.

Out slithered a sinister golden form with glittering green eyes!

Beyond that entrance, a tall, sinister form was awaiting him.

The sinister black form was advancing on him slowly.

That tall, sinister form stood in vague outline before the quiet house.

When next the sinister form appeared, it was standing before the door of an apartment.

Out stepped the sinister form that had developed within.

These lakes soon take on a more sinister form.