‘That’s a bit drastic though, isn’t it?’ Vincent put in doubtfully.

Trudy snorted inelegantly. ‘Huh! You weren’t there. Believe me, those two are a right poisonous pair. When it comes to hanging on to their own creature comforts, I think they’d be willing to do almost anything. Dr Ryder, don’t you agree?’ she again appealed to Clement to back her assessment.

‘Yes, they’re used to being the apple of their mother’s eye all right,’ Clement agreed at once. ‘And Millie struck me as being a very indulgent mother,’ he added for his son’s benefit.

‘Got it – they were worried she might start spending her money on the fancy man and not on them. Is that the lot?’ Vincent asked.

‘There’s the possible passenger in the car,’ Trudy added, a shade uncertainly, and explained about the unsatisfactory sighting of a passenger in Terry’s car, which might tie in to the indistinct footprints that were found leading away from the crash scene.

‘But presumably the passenger can’t be the killer,’ Vincent objected after a moment’s thought. ‘You don’t give someone a sleeping dose then get in the car with them, do you? You might end up wrapped around a tree yourself.’

Clement and Trudy, who’d both already considered this, nodded in agreement. ‘Unless he or she wanted to make certain Terry died,’ Clement felt obliged to play devil’s advocate. ‘He or she gave him the dose then got in the car, just to make sure he didn’t make it home in time to stumble into bed, safe and sound.’

‘Yes. It is, when you think about it, a rather iffy way of trying to kill someone, isn’t it?’ Trudy mused out loud. ‘Presumably the killer knew the dose itself wouldn’t be fatal, so would have been counting on Terry crashing the car and dying as a result, or freezing to death afterwards. Hold on!’ She sat forward suddenly as something occurred to her. ‘So he or she would have had to have got the timing just right!’ she pointed out, her voice rising with excitement.

‘Yes!’ Vincent cried, her excitement catching. ‘If they’d given it to him too soon, he’d just have got sleepy and fallen asleep on the couch or something. And Mrs Vander would have been sure to let him just sleep it off.’

‘How was it done?’ Trudy asked, momentarily stumped. ‘How could the killer have known just when to give him a doctored drink?’ she asked, looking and sounding baffled.