He had done everything he could think of for the present, but the knowledge of this fact deepened rather than lessened his anxiety. The whole affair was so extraordinary that he had an instinctive feeling that there must be something evil at the back of it. Was it likely or even possible that the summons which Nancy had received could really have come from Mr. Penwarren? Even if he were in town, for what conceivable reason could he have sent to fetch her at eight o'clock in the morning? And yet, knowing Nancy's character, it seemed equally incredible that she should have left the studio under such circumstances, without being absolutely convinced that the message was a genuine one.

If she had fallen into a trap, there could be no doubt whose hand had set it. The affair in Flood Lane proved that, whatever motive lurked behind Fenton's proceedings, he had now reached a point where nothing would be allowed to stand in his way. He was certainly quite capable of having abducted Nancy, though, in view of the hue and cry which he must have known would immediately follow, it was difficult to imagine how he could have hoped to avoid discovery. From all appearances it seemed to be either the work of a madman, or else the final stroke in some deliberate scheme, the apparent weaknesses of which had been carefully guarded against.

It was the dread of this latter alternative which was clutching at Colin's heart as he once more reached the corner of Jubilee Place. Should it prove to be the true explanation, every minute was obviously of the greatest value, and the prospect of remaining idle for the next two hours filled him with an almost intolerable revolt.

Unless he could get hold of Marsden personally, however, it seemed useless to communicate with the police until he had received a reply from Helston. They were not likely to take action on mere suspicion, especially when the Inspector himself had promised to be on the spot at two o'clock. As to whether there was any chance of his arriving earlier Colin had no idea, but, since the only other course was to do nothing, he decided that he might just as well drive up to Whitehall straight away.

With this resolve he started the car, and, turning down through Burton Court on to the Embankment, swung round to the left in the direction of Westminster Bridge. A sharp run of about seven minutes brought him to the Yard gates, where, as usual, a couple of stalwart-looking constables were standing on duty. Colin recognized one of them as his acquaintance of the previous day, and with a friendly nod he pulled up alongside.

"That's all right, sir," observed the man approvingly. "No objection to your coming in now we know who you are."

Colin leaned forward from the driving seat.

"Do you happen to know whether Mr. Marsden is about anywhere?" he asked. "He made an appointment with me for two o'clock, but something rather important has cropped up, and if possible I should like to see him at once."

"He hasn't been in this way," was the policeman's answer, "but he might have come along by one of the other entrances. You can go inside and inquire, if you like. The officer on duty will be able to find out for you."

Colin thanked him, and, steering his car through the gates, came to a halt in front of the broad flight of steps which led up to the main door.