Still nothing from Felicity. Had she fallen asleep on the job?

Maria pulled the walkie-talkie out of her belt, where it occupied a place next to her empty holster, and tried once more to contact her partner. "Are you there?" she asked, with no small annoyance.

To her relieved surprise, the speaker finally crackled to life. But relief gave way to unease as a harsh whisper came over the channel.

"Maria, is that you?"

"You're going to have to speak up! There's a lot of static."

"Shh! Not so loud," the voice rasped. "He'll hear you."

"Who'll hear me? Aren't you supposed to be alone over there?" asked Maria. Felicity had never been the type to cryptically dance around a problem. "Wait, you still have my gun, right?"

"Never mind about that."

Why was Felicity whispering, assuming this was even her? Hoarse as the voice was, it was impossible to be sure.

"What do you mean, never mind?" said Maria. "If Noelle finds out, we're in trouble. It was a gift!"

The day before, Maria broke Felicity's handgun. Felicity had been walking her through some quick disassembly techniques, and in a moment of clumsiness, Maria damaged the extractor. Apologizing profusely, she agreed to let Felicity borrow her revolver until the part was replaced.

"It'll be fine. Say, Maria," asked the voice, "would you do me another favor?"

Her eyes narrowed. This smelled as rancid as two-month-old fly food. "Like what?"

"Could you leave a few things in the hall by Dr. Palmstroem's door?"

"But you aren't even supposed to be patrolling this wing tonight."

"It's for an experiment."

An experiment! In spite of her better judgment, Maria's curiosity was piqued. "Really?"

"I'll need a bottle of antifreeze and a paintbrush. For testing some chemical properties."

"Like... toxicity?" Maria asked, then inwardly cursed herself for the anxiety in her voice.

"No, no, heavens no. It'd be easier if I just showed you. Leave the antifreeze and paintbrush by Dr. Palmstroem's door, and I'll give back your gun."

"Um, I don't think this is a good idea."

"You could always tell him. But then Noelle would have to find out about the gun, wouldn't she?"

"Wait, you begged me to lend it to you! Why are you acting like this?"

"I just don't want us to get caught."

What a mess. Maybe if she played along for the time being, she'd learn more about what was going on.

"Fine," said Maria. "But I'm never lending you anything again."

Perhaps she should have simply refused — but that's not how it happened.

The fabricators in the machining room needed antifreeze to keep from overheating, so Maria started her search there. As she entered, she suppressed an involuntary shudder of recollection. The bulky fabricators still filled the far side of the room, and it even looked like they'd kept the same crowbar.

Inside the chemical cabinet, she found what she was looking for: a plastic gallon jug of antifreeze on the top shelf. Standing on tiptoe and stretching, she snagged the handle with her fingertips and pulled it down, nearly dropping it in the process. A little blue-green liquid streaked down the sides of the container, which was labeled:

EZ-TRACE ANTIFREEZE & COOLANT

With UV DYE for leak tracing

Instructions: Add to fill line. Do not overfill. Do not ingest. For best results, trace leaks in dark environment with UV flashlight.

She shut the machining room door behind her.

As for the paintbrush, the fly-sorting station in Animal Testing had a coffee can full of them. If the voice had wanted something bigger, that was their problem. But as soon as Maria entered and flipped on the lights for the second time that night, something struck her as subtly different in the room. It was only after she had retrieved the brush and was heading back to the door that she realized what that change was.

Where there had been only one mouse earlier, there were now two.

The cage was still locked, and Maria was certain it contained no place to hide an entire mouse. And yet there the surplus rodent was: identical to the first in all visible detail, save that only two of the LEDs on its harness were lit, as opposed to all three. While it was conceivable that someone slipped into the room during her conversation with her uncle, to what end would someone place a mouse in this cage so late at night?

"It couldn't have just appeared out of nowhere," muttered Maria. "That would violate the Law of Conservation of Mouse!"

OPTIONAL PUZZLE: (Solved)

There is something Maria can do now to gather clues about this mysterious mouse cage. She cannot unlock or break into the cage itself, but she set up something else that may pay dividends later.

✓ Narration Unlocked by SmolShrimpa: Planning Ahead

Spoiler: How to plan ahead

The only thing to do, Maria decided, was to gather data. Whatever had just gone on in that cage, the audiovisual setup pointed at the mouse cage would be a perfect way to catch it on tape if it happened again.

She plugged the camera back in, made sure it the box was set to record to a new file if a sound triggered it, and tried to think of an excuse for Uncle Johann if he found his equipment tampered with. The best she could come up with was "Didn't you always want me to follow my curiosity?"

Frankly, it rang hollow. Better to hope he never found out.

That preparatory measure taken, Maria returned to the hall, her footsteps echoing hollowly through the dark. Half-expecting to be interrupted by the cryptic voice at any moment, she followed the radioed instructions, placing the brush and antifreeze directly under the miniature whiteboard hanging next to Uncle Johann's door.

Then she waited a few minutes. Nothing. Time to plot her next move. What would Noelle have done?

She'd seen nobody besides herself and Uncle Johann, and he was still taking his nap. Maybe Felicity, or some unknown mouse-planting intruder, had hidden somewhere.

But to hide, they'd have to get up here in the first place. There were only two entrances to this floor: the fire door near the machining room, which was protected by an alarm, and the east wing elevator. No alarm had sounded, so that left the elevator.

Good. The east and west wing elevators automatically recorded all keycard use on the lobby computer. And that would surely let her trace the movements of this... mouse reverse-kidnapper. Mouse-deliverer. Whatever.

Maria swiped her keycard through the slot on the elevator panel and rode it down to the ground floor. A short hallway led her to the lobby.

She scanned for intruders with a slow sweep of her flashlight. The beam cast spidery shadows against the wall as it moved across the potted plants and over the visitor couches, but nobody crouched there to pounce. As she approached the tall glass front doors, she made a point of walking on the runner carpet, where her steps would be silent, and not the tiles. She felt a little abashed at this, like a child sneaking downstairs for a midnight snack. But she was alone and unarmed, and if there really was an intruder, she'd rather have the advantage of stealth.

The big brass handles of the doors didn't budge when tugged sharply. Definitely locked. Only three cars were parked in the lot outside: hers, Felicity's, and Uncle Johann's. Good. Turning around, she looked up into the camera monitoring the entrance. Its indicator light blinked reassuringly.

Next, she checked behind the long, curved wooden counter that blocked off the reception area from the rest of the room. All was dark and quiet, save for the occasional roar of a revving engine from the nearby freeway. In the back were a cubicle, some copiers, and a storage space. A quick search found nobody there, either. The only other exit from the lobby was another hallway, opposite the one Maria had entered from, which led to the west wing elevators.

Time to check the keycard records. Maria slipped behind the desk and turned on the computer. A password screen greeted her.

The orientation packet had said that if she ever needed to work the front desk, a guest password was hidden under the keyboard. This seemed like a lousy security practice, but when she found the note written in her uncle's hand in lab marker, she understood.

[For readers who cannot see the image: The fragments of the sentence are MPUT, DQU, OTH, SSW, SRE, EEN, ECO, ERI, ORDT, and THEPA]

You just have to put the pieces together, she could almost hear him say.

✓ Narration unlocked by SmolShrimpa: The Computer Password

Spoiler: Unlocked narration w/ password

Using a notepad app on her phone, Maria rearranged the fragments until she found a sentence:

THEPA SSW ORDT OTH ECO MPUT ERI SRE DQU EEN

The username guest and the password REDQUEEN worked as expected, and soon she had full access to the keycard records.

There was definitely a problem here. And that problem... was that there was no problem. Nothing unusual whatsoever. With the exception of Uncle Johann, everyone who had arrived to work that day also left. And the only records of after-hours keycard use showed Maria arriving early and beginning her patrol of the east wing, and Felicity arriving late and patrolling the west wing.

Her mysterious mouse-depositor had left no tracks.

Having acquired this baffling evidence, Maria took the east wing elevator back upstairs. Perhaps Uncle Johann would be awake by now, and could discuss what to do. But only moments after she reached the fourth floor, a gunshot rang out from her uncle's office.

Heedless of her own safety, Maria rushed to the door. "Stop!" she cried out. "Security! Drop your weapon!"

The only reply was the muffled noise of a struggle. She rattled the door furiously; bolted from the inside. Then a second gunshot pierced the air, and the tumult of fighting ceased.

"Felicity!" Maria shouted into her walkie-talkie. "Wake up! Get over —"

She froze mid-sentence. Through the thick door, she'd heard her own words echoed on the other side. But that meant —

Maria needed backup, backup that was not Felicity, and she needed it at once. She ducked away from the office door, keeping herself out of a shooter's line of fire, just as she'd been trained.

🔒OPTIONAL PUZZLE: (Solved)

Maria needs a way to summon help quickly. She has no cell phone reception, she can't trust the voice on the walkie-talkie, and there's no time to take the elevator.

What is the fastest way for her to get some attention?

✓ Narration unlocked by MortimusWasHere: Getting Help

Spoiler: Spoiler

Then she hurled herself at the fire door.

An ear-splitting alarm clamored through the building, and doubtless the entire neighborhood. Maria winced, but the din would do its job. Soon, the fire department would come, and she'd have backup. Then she could see what happened to Uncle Johann without putting her life at risk. She just had to wait, to hold out for help. Nothing good would come of charging into Uncle Johann's office unarmed.

So she stood there in the desolate hallway, covering her ears with her hands and watching the office door warily, ready to bolt for the stairs if anyone emerged. Nobody did.

And as she stood, certain thoughts began to intrude.

How long does it take to bleed to death from two gunshot wounds?

If Uncle Johann dies now, will it be my fault?

They're going to ask why I didn't have a gun.

I need to do something.

Why am I not doing something?

I need to do something now!

Maria grabbed the crowbar from the machining room, rushed backed to the office door, and pried and tugged with all her might. The wood splintered, the door swung open unsteadily, and inside she saw...

...her Uncle Johann, dead. And nobody else.

Uncle Johann was dead, and Maria knew it even before she knelt by his side and checked the pulse on his still-warm wrist, even before she turned him over to see a single bullet wound in his chest. Close range, a quiet part of her mind noted, remembering what she'd learned from Noelle. Contact shot, powder burns.

Uncle Johann was dead, and Maria recognized her own gun on the floor beside him. She did not touch it. She would not touch anything else. She knew better.

Uncle Johann was dead, and Maria clutched the crowbar in shaking hands, steadied her breathing, and numbly ticked off a mental checklist. Search the room for the killer. Definitely check behind that partition. Make sure nobody is hiding. Nobody was, though there was a big puddle of something blue-green there. Antifreeze? And there was a tripod in the puddle.

She looked out the window: open, with a clear line of sight to the west wing. Nobody on the ground below, but it was hard to see in the dark.

Uncle Johann was dead, and Maria, who was certainly not panicking, methodically checked for clues while waiting for backup. Signs of a struggle — dolls, books, and a globe knocked off the bookshelf. But not always consistent signs. Why was the pillow near the desk where her uncle slept, while the gun was near the body, and that stack of papers was scattered near the partition in the back? Two different struggles, or one struggle that moved around the room?

She photographed the scene, aiming her phone and taking shots with a vague sense of unreality.

Time passed in a daze. Soon, Felicity arrived and tried to calm Maria in spite of being deeply shaken herself. Then a firefighter came, followed soon after by Noelle, who had been summoned by Felicity's panicked call from the lobby phone. More police, who dismissed the firefighter. Then the feds, who dismissed most of the police.

But it wasn't until Maria sat in the downstairs conference room, relating her story in full, that she truly understood...

Uncle Johann was dead.