The living flung themselves blindly at the walls, some dropping stunned with the impact, lying inert for several moments and then recovering surprisingly quickly, piping their rage and hurling themselves back at the glass again. Some eight or nine lay dead below the maddened twenty or so that continued their crazed aerobatics in the cramped enclosure.

One small, reddish-brown silky body attempted to secure a hold on the smooth sides of the case with its minute claws, slipped, and fell to the floor. It rolled onto its back, kicking frantically at first, then slowly the twitching limbs stiffened as though rigor mortis were preceding death. Yet the two watching humans knew by the way the bat's eyes dilated that it still lived. They realised also that it was in indescribable pain—and there was nothing whatsoever that they could do about it.

It was a quarter of an hour before the bat's eyes dulled and it died. The last victim, an hour ago, had suffered for forty-five minutes before it was granted a merciful release from its suffering.

'Hell,' the tall man muttered to himself, 'I've never seen anything like it before!'

The girl moved closer to him, and asked in a low, husky whisper, 'What is it, Brian? What's happening to them?'

He seemed to notice her presence for the first time, and his expression softened momentarily. 'I don't know,' he murmured, averting his eyes from her gaze.

'But. . . ' her fingers closed over his as she spoke, and he made no attempt to remove them. 'The tests. The tests we did yesterday. They're bound to show something . . . the reason for this paralysis in the bats, the mad rages, the pain ...'

Professor Brian Newman looked silently out of the window. Out there, across the soft, springy heather which was just beginning its new growth, were something in the region of twenty-five thousand acres of woodland and heath—Cannock Chase, a well-known beauty spot to which crowds of tourists thronged at weekends and on bank-holidays. A natural environment, except for this place, the Midlands Biological Research Centre, an ugly scar on the landscape.