‘And if anyone was abroad in the night on the road from Crossdyke to Ramsdyke they might have seen an antic show: a man on a Route-Rocket with what seemed to be either a very affectionate or a very drunken rider on his pillion: a rider whose head lolled and jerked preposterously and who seemed to be glued to his back.’

‘What about the suitcase?’ asked Tillottson.

‘Made fast. It’s not weighted at this stage. The stones were collected at the weir.’

‘Roadside heap,’ Fox put in. ‘Loose brick. Shingle. We’ve got all that.’

‘Exactly, Br’er Fox. Fish out a sponge from my bag, would you?’

Fox did so. Alleyn pressed it over the surfaces of the diary, mopping up the water that seeped out. ‘It’s when he gets to Ramsdyke,’ he went on, ‘that the cyclist’s toughest job begins. Presumably he’s single-handed. He has to dismount, carry his burden, a ghastly pick-a-back, presumably, down to the weir. He unlooses and dumps it, returns for the case, puts in the stones and shingle, humps the case to the body, adds a loose half-brick, ties the body to the case and pushes both of them far enough along the footbridge to topple them into the weir.’

‘Do I,’ Fox blandly inquired, ‘hear the little word conjecture?’

‘If you do you can shut up about it. But you don’t hear it all that clearly, old boy. Find me another theory that fits the facts and I’ll eat the dust.’

‘I won’t give you the satisfaction, Mr Alleyn.’

‘Find something to slide under the diary, will you? I want to turn it over. A stiff card will do. Good. Here we go. Now, the sponge again. Yes. Well, from here, the sinister cyclist and his moll begin to set-up their disappearing act. All we know is that they had paid their bill at the Star and that they lit off some time that night or early next morning. Presumably with a fabulous Fabergé bibelot representing the Signs of the Zodiac in their possession.’

‘Hi!’ Tillottson ejaculated. ‘D’you reckon?’

‘This really is conjecture,’ Alleyn said. ‘But I don’t mind betting we do not find the damned jewel on board the Zodiac.’

‘River bed? Swept off the body, like?’

‘I don’t see him leaving it on the body, you know.’

‘I suppose not. No.’

‘It may have been the motive,’ Fox said. ‘If it’s all that fabulous.’

‘Or it may have been a particularly lush extra: a kind of bonus in the general scheme of awards.’

Tillottson said: ‘You don’t lean to the notion that this cyclist character—’

‘Call him Smith,’ Fox suggested sourly. ‘I’ll bet nobody else ever has.’

‘This Smith, then. You don’t fancy he did the killing?’