I arrived home on a crisp October morning to find my roommate, Arthur, heralding disaster.

He was sitting in our apartment’s front room, typing so furiously at the dining table that the laptop’s keystrokes ran together like a snare roll. This was the first warning sign—not so much the frenetic typing as the fact that he was out of bed. The clock had just hit 10 am, and Arthur Leung was the kind of borderline nocturnal computer person who never crawled into the sunlight before eleven except for emergencies.

The second red flag: his full-body twitch when I opened the door. Cat meets spray bottle. His head jerked up, and for a moment, he didn’t move.

Then he shook back his hair and declared, in the voice of someone whose kidnapper has told them to act natural, “Oh, hey, Parker! What’s up! How was”—his eyes lit on the bags in my hands—“the grocery store!”

“Um,” I said, toeing off my shoes on the doormat. “The store was normal.”

“You were going to get yogurt, right? Did you get yogurt?”

“I did.” I paused. “Was the yogurt an urgent thing for you?”

“No! It’s fine, it’s all good.”

I set the bags on the kitchen counter, still watching Arthur. In an interrogation room the guy would have folded like wet cardboard. He avoided my eyes, his foot bouncing so that reverberations went through all six foot three of him. Within seconds, a pale sheen had developed on his forehead.

“So,” I said slowly. “What’s going on, man? Is everything okay?”

A muscle ticked in his jaw. Before I could ask if his friends and family still had all their limbs, he slammed his laptop shut and said, “Don’t go online.”

My concern shriveled into a hard pit of dread. “Arthur. What happened?”

But I already knew the answer.