Her toes were driving steadily into the front of her running shoes. Her ears were starting to ache in the cold. She tightened the drawstring of her hood beneath her chin, and from her jacket pocket, she took a pair of mittens and pulled them on, blowing into her hands and pressing them against her chilled face.

Ahead, the river separated into two parts- main body and murky stream-as it fl owed sluggishly round Robinson Crusoe’s Island, a small mass of land thickly overgrown on its south end with trees and brush and its north end given to the repair of the colleges’ sculls, canoes, row-boats, and punts. A bonfi re had been lit in the area recently, for Elena could smell its remains in the air. Someone had probably camped illegally on the north section of the island during the night, leaving behind a residue of charred wood hastily extinguished by water. It smelled different from a fi re that has died a natural death.

Curious, Elena looked through the trees as she dashed along the north end of the island. Canoes and punts piled one on top of another, their wood slick and glistening and dripping with the fog. But no one was there.

The path began the rise towards Fen Causeway, which marked the end of the fi rst leg of her run. As always, she met the gradual acclivity with a fresh burst of energy, breathing steadily but feeling the building pressure in her chest. She was just beginning to adjust to the new speed when she saw them.

Two figures appeared ahead of her on the pavement, one crouched and the other stretched across the width of the path. They were shadowy and largely amorphous, and they seemed to tremble like uncertain holograms, backlit by the wavering, fi ltered light from the causeway about twenty yards away. Perhaps hearing Elena’s approach, the crouched figure turned towards her, lifted a hand. The other didn’t move.