“Infundibular,” Everett whispered, in the screen-light, under his duvet, with a mid-December storm gusting and howling around the eaves. He remembered where he'd heard that word before.

Tejendra had been a late convert to Dr. Who. He became a fan after he had a place of his own, where he could watch without Laura shaking her head at the geekiness of it all. It was all right for kids, but for grown men…After a Saturday game, or a wander up the Lea Valley, Everett and his dad would sit down and watch the show while their latest culinary creation evolved on the hob. “Infundibular,” Tejendra had said. “That thing, that police box. Bigger on the inside than the outside. It's easy in maths, having things that are much bigger on the inside than the outside. Now, if they were really clever, they'd make it properly infundibular, which is, the farther you go in, the bigger it gets. There'd be a smaller box inside that box, but that box would be bigger on the inside than the one containing it, and inside that one, a smaller box that was even bigger inside and so on, all the way down, so that by the time you got to the centre, it would be smaller than an electron but inside it would be bigger than the entire visible universe.”

Infundibulum. The farther in you go, the bigger it gets. There was no doubt in Everett's mind about who had left the anonymous folder in his drop box. Neither was there any doubt that this was what Paul McCabe had been asking about with his parting question. He had tried to make it sound so offhand, but it was the only reason he had come to the house. Sudden fear knotted at the base of Everett's stomach. Paul McCabe knew about this Infundibulum, and it was important to him. Did he know what it was? To Everett it was eerie mathematical patterns, sent by his father to him and him alone. To Paul McCabe it was important enough to drive an hour and a half around the M25 to slide it in as a casual aside. Did he not have access to it? Had Tejendra not wanted him to have it? Had Tejendra not trusted his own department head with it? Was Everett the only one Tejendra could trust with it?

Everett clicked down the silent, swirling hypnotic ghost-patterns. He went back to the drop box. The file had been uploaded at eight. Tejendra had been driven away in the black Audi at six. Everett was sure that whoever kidnapped him would not have handed him a laptop and said, Sorry, we forgot, go on, please upload that file of abstruse mathematics.

He remembered the attached note. Four words: For you only, Everett. No name, no signature, no greeting or sign off. For you only, Everett.