The police gave the go-ahead to build the “giant mousetrap” that Kitamura-san dreamed up. The general outline went as follows.

Less than a mile from Ichiro’s house, a concrete storehouse stood alone in the middle of a field. During the war, air raids had destroyed all of the wood-frame houses on the block. The police borrowed the storehouse from the owner and refurbished it. They brought in lights, furniture such as a desk and a bed, and fitted it out just like an apartment where any person would feel at home.

They also installed a curious contraption in the entranceway whose purpose and design will become apparent later on.

Once the preparations had been completed, Yurika Hirano set up house by herself in the concrete storehouse. One day, without any fanfare, she traveled there by car and moved in. Every day, she practiced her violin and lived her life and did whatever she was otherwise wont to do.

A small two-story apartment building occupied one edge of the far side of the field. The same day that Yurika moved in, a man rented a room on the second floor. A man in his thirties, he appeared to be a regular office worker, except he never went to work. He stayed holed up in the apartment all day long, peering out at the field from a crack in the curtains.

The window faced the front door of the concrete storehouse where Yurika was living. He would spot anyone entering or leaving the storehouse at a glance.

Not only that. Inside the room was an electrical panel with switches. Now and then, the man pressed one of them. The buttons were labeled with odd words like “Music” and “Lights” and “Gas.”

Now and then, a visitor covertly arrived at the stakeout apartment. Sometimes the visitor was an adult, sometimes a young man. The young man was none other than Yoshio Kobayashi, Detective Akechi’s assistant.

Using a prearranged code, Yoshio knocked on the door and entered the apartment. He sidled up to the man there and whispered, “Has anything happened?”

The man whispered back, “Not yet. This guy won’t show his face until after dark. He’s gonna show up tonight. I can just feel it. And fall right into our clutches.”

“Will you be able to see him after dark?”

“That won’t be a problem. There’s a light next to the front door of the storehouse. The lenses in these binoculars let in a lot of light. All the way from here, it’s like I’m standing only a few feet away.”

In short, this vigilant man was a highly capable member of the Metropolitan Police Department. He was keeping the storehouse under surveillance in order to capture the space alien.

The necessary preparations had been completed to take the creepy creature into custody. All they had to do was wait for it to sneak into the concrete storehouse. What was going to happen that night? Would the monster at last end up caught in their trap?

Many questions remained up in the air. What was the contraption affixed to the entranceway of the storehouse? What was the purpose of the switchboard in the stakeout apartment, and the meaning of the labels like “Music” and “Gas” next to the buttons?

There were graver concerns. Supposing the alien fell into their trap, what would become of Yurika? Could the alien be ensnared while Yurika alone ran away? And even if she could, wouldn’t Yurika be placed in terrifying peril? What would compel Yurika and her father to go along with such a plan?

The alien finally showed up that night. Wearing the same overcoat and felt hat and silver mask, it appeared in the field from seemingly out of nowhere.

The beautiful sounds of Yurika’s violin floated faintly from inside the concrete storehouse. As if entranced by the music itself, the alien crept closer to the back of the storehouse. A small window, fortified with iron bars, was cut into the back wall. The alien scanned its surroundings, then leapt up onto the window sill, grasped the bars, and peered inside.

Inside the storehouse, a desk lamp with a blue shade filled the room with a wan glow. On the other side of the table stood Yurika, all her attention directed to her violin. The alien pressed its eerie silver face closer to the bars and stared at Yurika. Yurika did not register its presence in the slightest.

At length, the alien climbed down from the window and with its strange gait slowly circled around to the front of the storehouse.

A pair of heavy double steel doors was set into the front of the storehouse. The alien approached the doors and investigated the lock. Having determined that the doors were not locked, it placed its hands on the doors and softly cracked them open, no more than an inch, and peered inside through the gap.

Facing the other way, Yurika was still practicing her violin. She didn’t notice the doors ever so slightly ajar behind her.

Little by little, one of the doors began to move as the alien cautiously opened it wider. The gap grew larger. An interminable time later, steps muffled, not raising a sound, the alien stepped inside—

At that moment, a startling sound rang out. With a loud clang and a harsh thump, a heavy gate fell into place from above. The alien jumped in surprise and whirled around to find the sole exit from the storehouse blocked by a set of iron bars.

For all its technology and intelligence, the space alien had not seen this coming. One of the floorboards right inside the entranceway had a bit of give to it. Stepping on it pressed a switch beneath the floor that released an electric hoist suspending the iron bars above the front doors. The gate then promptly clanked down into place.

In short, the same mechanism as a mousetrap enlarged a hundred times.

The alien leapt at the iron bars and attempted to raise the gate. But the formidable lattice of iron bars was too heavy for even the alien and all its strength to budge. The alien was now a prisoner in a cage, captured in a giant mouse trap that none of its magical powers could free it from.

Except the alien had not been taken prisoner alone. Yurika was in the storehouse as well. She appeared to be facing the other way, standing there still as a statue.

Realizing there was no escape, the alien spun around and glared at Yurika. Then it raised its arms, spread its fingers wide, and sprang at her. Ah, what was going on? Were the police so eager to capture the alien that they were willing to sacrifice this beautiful girl? Did not Yurika care that she was about to become a victim of its murderous impulses?

How could the police even begin to contemplate something so outrageous?