Porter kept to the right of the prints and followed them beyond the first line of trees. He paused twenty feet in when they seemed to end abruptly, but saw they started up again a few feet further on. He glanced back over his shoulder but the path had vanished behind a screen of leaves. Time check. He had three minutes left of his allotted five. The tracks stopped suddenly by a huge oak. The trunk was so large that Porter doubted he could circle it with his arms. Branches, too many to count, reached upwards, clawing against each other, competing for sunlight. He did a lap of the tree to see if she had gone further in, but the ground either side was untouched. He squatted again and looked at the marks closest to the tree. Two outlines sat side by side, as if she’d stood on the spot for some reason.

Satisfied this was as far as she had gone, Porter did another circuit of the tree, less concerned now about scuffing her trail. He walked slowly, staring at the base. The roots rippled outwards like octopus’s tentacles, but the soil was undisturbed. If she had left anything behind it wasn’t here. The only thing that broke the monotony of rough bark was a patch of snowdrops on the far side, shaped like a giant teardrop by what light and rain could battle its way down to help them grow. He looked at his watch. Time to head back or he’d risk losing her. He spun a last lazy circle before retracing his steps back to the path.

Damn it! What the hell was she playing at?

It started as the vaguest of notions but grew in an instant, then hit him full force, and if he was right this would change everything.

They spotted Mary Locke sitting in the far corner when they got there. It was a bright, homely place; the big glass front unobscured by curtains or signage allowed the sunlight access to all areas. It wasn’t the kind of place she could hide in a dark shadowy booth at the back, but Porter assumed that burrowing herself away in the corner made her feel somewhat more secure.

They were the only customers, and the waitress intercepted them before they’d pulled chairs out from the table. They both ordered black coffee in cardboard take-out cups. There was no telling how quickly the clandestine meeting might end. Mary Locke didn’t rise to greet them, didn’t even look up from her cup, head bowed and glasses resting just above her hairline. Porter caught a whiff of peppermint from her teabag as she submerged it repeatedly on her teaspoon, like a witch on a ducking stool.