He was driving his own car with Alleyn and Fox as passengers. The London CID car followed with a driver, a local constable and Sergeants Thompson and Bailey who had been pressed in as an emergency measure.

Sirens could be heard without definition as to place or distance. Road blocks and search parties from Longminster, Norminster and Crossdyke were being established about the landscape.

With that dramatic suddenness created by fog, a constable flashing an amber torchlight stood in their path. ‘Well?’ Tillottson said, leaning out of the window.

‘This is as far as you can drive, sir.’

‘Where’s Cape?’

‘T’other side, sir.’

They got out. Close on their left hand the fog-masked weir kept up its anonymous thunder. They followed the constable along the tow-path to the flight of steps that led up to the main bridge.

‘All right,’ Tillottson said. ‘Get back to your point.’

As they groped their way over the bridge a car crept past them filled with revellers engaged in doleful song.

The constable stepped into its path and waved his torch.

‘Hullo-’ullo-‘ullo,’ shouted the driver. ‘Anything wrong, Officer?’

‘Just a minute, if you please, sir.’

‘Our Breath is as the Breath of Spring,’ someone in the back seat sang dismally.

‘May I see your licence, sir?’

When this formality was completed Alleyn and Tillottson moved in. Had they, Alleyn asked, seen a solitary woman? They replied merrily that they’d had no such luck and emitted wolf-like whistles. Alleyn said: ‘If we weren’t so busy we’d have something to say to you. As it is, will you pull yourselves together, proceed on your silly journey, stop if you see a solitary woman, and address her decently. If she’s got a strong American accent, offer her a lift, behave yourselves and drive her to the nearest police stop or police station, whichever comes first. Do you understand?’

‘Er—yes. Righty-jolly-ho. Fair enough,’ said the driver, taken aback as much by Alleyn’s manner and voice as by what he said. The passengers had become very quiet.

‘Repeat it, if you please.’

He did.

‘Thank you. Drive carefully. We’ve got your number. Goodnight.’

They crawled away.

Bailey and Thompson and their driver loomed up and the whole party inched along until they found the top of a flight of steps going down to the lock.

‘What can have got into her?’ Fox mused, not for the first time.

‘Fear,’ said Alleyn. ‘She was terrified. She’s tried to do a bolt. And succeeded, blast it. The Skipper must have delayed—hallo, here we are. That’s the roof of the lockhouse down there. Come on and for God’s sake don’t let’s have any falling into the lock. Easy as we go, now.’

They felt their way down the steps to the tow-path.

‘Cape!’ Tillottson shouted in a terrible voice.

‘Here, sir.’