"I wonder--"

She never finished her sentence. From their table, which was nearest
to the door, they were suddenly aware of a commotion of some sort
going on just outside. Through the glass door Rosario was plainly
visible, his sleekness ruffled, his white face distorted with
terror. The hand of some unseen person was gripping him by the
throat, bearing him backwards. There was a shout and they both saw
the cloakroom attendant spring over his counter. Something glittered
in the dim light--a flash of blue polished steel. There was a gleam
in the air, a horrible cry, and Rosario collapsed upon the floor.
Arnold, who was already on his feet and half-way to the door, caught
one glimpse of the upstretched hand, and all his senses were
thrilled with what he saw. Upon the little finger was a signet ring
with a scarlet stone!

The whole affair was a matter of seconds, yet Arnold dashed through
the door to find Rosario a crumpled-up heap, the cloakroom attendant
bending over him, and no one else in the vestibule. Then the people
began to stream in--the hall porter, the lift man, some loiterers
from the outer hall. The cloakroom attendant sprang to his feet. He
seemed dazed.

"Stop him!" he shouted. "Stop him!"

The little group in the doorway looked at one another.

"He went that way!" the cloakroom attendant cried out again. "He
passed through that door!"