“Research laboratories, storage rooms, data centers, electrical stations,” Hailey had explained. “But I couldn’t tell you for sure. There are so many of these tunnels, literally miles of them. They run under the entire campus, and there are multiple levels. They go on forever.”

Nick had looked behind them, then ahead. They seemed alone; the only sound had come from their own shoes against the cement floor.

“Do other students come down here?”

“On occasion. Actually, it’s kind of a rite of passage—hacking the tunnels. In fact, one graduating class put a partial map of the system on their class ring. But I don’t think many people have explored all of it. Some of these tunnels go back decades, or longer. And there are plenty of secrets down here. This is MIT, after all.”

They had taken a hard right turn and descended down a narrow ramp, to another stretch of tunnel.

“Beginning before World War II,” Hailey continued, “MIT developed a very close relationship with the Department of Defense. A lot of advanced weapons and war technology was developed here, in secret labs, often using student research. Radar came from MIT, and tons of work on radiation. There’s even a nuclear reactor somewhere on campus.”

“For real?”

“A lot of these doors don’t have labels or nameplates for a reason. Things have changed over the years, but you don’t shed a history like that overnight.”

They’d gone the next ten minutes in near silence, Nick wondering how close they were to that nuclear reactor while Hailey followed some internal compass to wherever they were going.

When she finally came to a stop, Nick found himself in front of another unmarked door. Hailey worked the lock with a second key from her purse—and then ushered him inside.

*  *  *

Hailey hit the lights, bathing the rectangular space in a fluorescent glow. Even so, it took Nick’s eyes a moment to adjust, not because of the flickering ceiling tubes, or the fact that there were obviously no windows so deep below the campus; but because there was just so much to see, all at once, a visual barrage that had his rods and cones playing twister.