Bruno slid the key into the lock, turned it three times, and pulled open the metal door. “If you please, through here.”

It was a long, curving, narrow passageway, barely more than a yard wide, and on either side extremely high blank walls that were topped by a metal mesh that served as a roof. “There, you see? It’s a passageway that we never use, it’s just for us guards, only in case of accidents or emergencies. A single man can just fit through.” Biranson, followed in single file by Rocco and Marini, was walking along, stepping on the weeds that had sprung up in the cracks in the cement. “But we never use it.”

They came to another door. This one, too, all in metal. “Here we are. The corridor ends here.” Biranson pulled out his keys and opened that second rusted entrance. “After you . . .”

They found themselves just outside of the recreation courtyard, near the location of the brawl, facing Wing 2. “So, if I understand completely, this corridor links Wing 3 with the outside of the courtyard.”

“That’s correct, right next to Wing 2,” said Marini. “And there, you see? It’s right where Omar was attacked. In other words, it’s helpful for going around to the other side without having to go across the open plaza.”

“But we practically never use it!” Biranson said again.

“Biranson, the concept is clear to me,” Rocco said. “Now tell me, who has the keys to these doors and to the doors to the wings?”

“Saint Peter himself!” Biranson replied, hoisting two bunches with a dozen or so keys in all. “Anyone who’s at the courtyard gate is assigned to have the keys to the armored gates”—and here he raised the first metal ring—“and to these two metal gates”—and then he displayed the two remaining keys. “Dotto’, the same is true for the other gates—the ones leading to the other sections, I mean to say. There, too, they have an internal passageway, just like this one.” And he knocked his knuckles against the metal door. Rocco nodded.

“Do you want to go see this section?” Marini asked.

“No. I want to go talk to Agostino . . .”

“IT’S AN HONOR TO MAKE YOUR ACQUAINTANCE, DOTTOR Schiavone. I’ve read a great many things about you.”

Agostino Lumi, a.k.a. the Professor, had the kind of eyes that Rocco had seen on the faces of the worst bandits and armed robbers. Still, dead eyes, without a glimmer of expression, dry black river rocks. “You’re a talented policeman. Somebody just killed a friend of yours, a woman, right in your home, isn’t that right?”

“Nice to see you keep up with the news.”

“I read the newspaper every day. A German philosopher used to say that reading the newspaper—”

“—is the realist’s morning prayer,” Rocco finished his sentence for him.

“I see that we both studied the humanities.”