The motive of the actions taken that day by Eileen Meredith had been accurately diagnosed by Heldon Foyle. She had returned to her home after her visit to the police at Waterloo Bridge in a state of the keenest uncertainty. Not for an instant did she credit the paragraph referring to the dead body. The police had been able to read the cipher message from Grell, and she assumed correctly enough that they had been more successful than herself in obtaining an early glimpse of the advertisement. What, then, had become of her note of warning? She was half reclining in a big easy-chair, her arms resting on the broad ledges, her fists tightly clenched. Her train of thought led her to alarming conclusions. If the police had been watching--and that now occurred to her as having been an obvious step--they must not only have seen her note, but they might have secured and questioned the person who brought the advertisement. And if so, might not Robert Grell's hiding-place have been betrayed? Her heartbeats became unsteady. What if the visit of the detectives down the river had been not to identify a drowned corpse, but a living prisoner? Suppose Grell were already in their hands? She jumped to her feet. The watch on her wrist spoke to quarter to eleven. Her reflections had occupied many hours. She was already dressed in a brown walking costume, and she had not even removed her hat since she returned. In answer to her summons a maid appeared with a cup of coffee and a couple of biscuits on a tray. That reminded her that she had not eaten since she had risen. She drank the coffee and ate the biscuits, while waiting for the brougham she had ordered. Within a quarter of an hour she was on her way to Scotland Yard. In the circular hall, entered through swing-doors from the wide steps of the main entrance, a uniformed policeman hurried forward to take her card. Through the big windows she could see beneath her the surging life of the Embankment and the smooth traffic of the river. Had the river given up its secret? The constable returned, and she was ushered along a grey and green corridor to Foyle's room. He had his overcoat on, and his hat and stick lay on the table. He smiled a polite welcome at her, and she strove to read his genial face without success. For her there was something of humiliation in the situation. She, who had taken pains to be offensive on the last occasion that they had met, was now dependent upon his good-nature for the information she wanted. "What can I do for you, Lady Eileen?" he asked with grave courtesy. She had dropped into a chair and her grey eyes met his, half defiant, half entreating. She answered with quick directness-- "You can tell me what has happened to Mr. Grell." He opened his hands in a gesture of surprised expostulation. "My dear young lady! I only wish we knew."