At the top of the board, he had pinned a creased photograph of his mother and father, taken years before he was born: a young couple at some dim, happy party, his dad half-turned, blurring into red-black shadows. A vague, tall man, with black hair pushed back from a high forehead. It was the only picture Alex had ever seen of him. He couldn’t see him at all.

His father had died months before his birth. That’s what he had always been told, anyway. He felt certain his mother believed it. He had believed it like a law of nature himself until recently.

The rest of the board was covered in a mess of smudgy charcoal drawings, dozens, all variations on the same subject: a tall man in a long black coat and black hat. Sketches from memory of the figure who had hunted Alex and his grandfather across Europe with his strange gang and their weird machines, trying to steal back the toy robot and its clay tablet.

The tall man, Alex called him—although he had eventually given him another, secret, name, one he could still barely bring himself to utter. In some of Alex’s drawings, the somber figure was depicted in full, turned away. In others, he loomed in brutal close-up: rough portraits of a head completely swathed in ragged bandages beneath the hat, save for one terrible eye.

This mummified visage was the only way Alex had ever seen him clearly, up close, after the man had used the tablet to summon forces he couldn’t control. Alex flinched as he recalled white light falling from the Prague sky, turning poison-black as it struck down. It had burned the man terribly. But it was Alex who had killed him.

His breath caught as he replayed it again, the most intensely vivid memory of all: this tall, wounded figure leaping from a bridge into a raging river, trying to save his daughter, the unsettlingly strange little girl who had jumped first, diving in when she thought Alex had thrown the tablet into the water. The two of them dragged down under the lethal, boiling current.

Their phantom faces were always in his thoughts, the girl’s—Zia, the tall man had called her—sharp and clear, the man’s always just out of reach. Alex’s attempts to capture his likeness, the features beneath the bandages, had become a nightly ritual. But when he closed his eyes and tried to picture the face he had once glimpsed, it receded into the shadows.

Yet Alex felt it was as close as his own skin. Of all the secrets uncovered during his adventure, this was the one that overwhelmed him most. From vague hints dropped in conversations, from his distant impressions of the tall man, from the resemblance he had eventually noticed hidden in his grandfather’s face—from clues in his own mirror every morning—he was certain.

The tall man was his father.