Six good-sized demons, entering the world through four separate dull-gleaming cracks in reality. There was no helping it. She had to draw on the Phoenix. Even at the height of her academic practice, when she’d been pushing herself to the very limits of her own ability every day in the lab, she wouldn’t have been able to handle this much magic without summoning something to assist her.

It got easier every time to call the power of the Phoenix forth. In Old Faithful’s incursion it had taken her nearly three minutes of focused attention to the original binding spells. Now it was barely more than thirty seconds. To onlookers, Walden must seem to be standing frozen, but she was actually concentrating intensely. The corners of her vision lit with a tracery of gold as the blood vessels in her own eyes illuminated with power that was not hers. The frustrated howl in the back of her thoughts settled into focused silence. We keep the area clear, Walden told it.

The Phoenix didn’t mind that; if the pedestrians weren’t part of Walden’s own territory, then they were just in the way. However—it made an interested magical lunge in the direction of a passing bus.

No vehicles! Walden thought at it, in rather the tone you might say No ice cream! to a demanding group of children on a school trip.

The demon was disappointed, but resigned. It helped Walden to set up multiple circles of warding perimeters, cutting the danger area off from the rest of the street, dividing the separate incursions from each other and from the smorgasbord of shop displays before the invading demons realised what was happening. One or two hostile demons at a time would be much easier for the Marshals to cope with than six at once. Walden insisted that they make the perimeter visible to humans. It flared up in scarlet and gold, firebird colours, warning colours. Now to collapse those incursions—a shame she couldn’t push the demons back through them first, but at least there wouldn’t be more. It was complex, intricate work. A wild incursion was not nearly so neat and manageable as one created in a lab. Sweat was starting on her forehead and arms despite the chill of the winter evening, and she hadn’t the faintest idea where Mark had got to. Calling for help, hopefully.

“Dr Walden,” said someone crisply at her shoulder. “Which one’s the worst?”