My phone buzzed in my pocket, so I shifted the bag to my other hand and tapped my Bluetooth headset. It was, predictably, Sophia.

"Where's my Reuben, asshole?" she snapped.

I forced myself to stay calm. Forced a smile to my face. Tried not to think about what I was about to do to her, which would have made the smile both more genuine and more sinister. 

"The deli didn't have it ready when I arrived," I said half-truthfully. They'd been wrapping up the order when I walked in, but she didn't need to know that. "I'll be out of here in two minutes, back inside the building in eight, and upstairs in ten."

She was silent for a moment, then grunted. "Fine. [i]This[/i] time. But don't clock in until it's in my hands. And you'd better believe I'm going to check your timecard. We don't pay you to loiter."

I raised my eyebrows. She was clearly in a good mood, and I almost felt guilty for a moment. [i]Almost.[/i] But it wasn't about me—or even, really, her. My boss ran the division of the company whose sole job was to shift funds between various offshore accounts until no government on Earth knew how to tax us. She was greed personified, stiffing entire nations for the benefit of a few big-shots who were already impossibly rich. I was doing the world a favor.

I fast-walked back to the office, getting waved through the fast-track security line—and after a body-scan, a patdown, and a chemical sniff, was hustling toward the elevator to the executive penthouse. I checked my watch. Seven and a half minutes. Just enough time.

When I got out of the elevator, I palmed the credit card from my back pocket and walked down the empty hall to the janitor's closet in between the two bathrooms. It was locked, but there was plenty of space between the door and the frame, and the card popped the lock trivially. There were security cameras in the hall, yes, but to all but the most detailed examination it would look like I was simply going to the bathroom, and I'd have a few seconds of guaranteed privacy.

I closed the door behind me, carefully unwrapped the Reuben, and extracted a small bottle of eyedrops from my briefcase. Or what [i]looked[/i] like eyedrops, anyway. I allowed myself a smirk as I uncapped it, levered the sandwich open with the back of my fingernail, and squeezed a single drop onto the corned beef. Then I carefully re-wrapped everything and put it back in the bag.

Odorless. Tasteless. Undetectable. It was the perfect poison.

It was the perfect crime.

[hr]

"Hey, Tanner," Riggs said through a mouthful of BLT as she stared at the security monitors. "Remember I had you scan that guy's meds in the fast-track line?"

Tanner walked over, crossing his arms. "Yeah?"

Riggs grinned and pointed at a screen. "And remember I told you about our penthouse murderer? Check it out—he's at it again."

Tanner glanced at the feed from the penthouse janitor's closet and raised an eyebrow. "I don't get it. That eyedrop bottle is water. [i]Literally[/i] water. Not even spit—it swabbed clean of DNA."

"Ah," Riggs said, lifting a finger. "But our perp did some of his web research from the office. What do you know about homeopathy?"

Tanner thought. "Medical pseudoscience. Something about 'like cures like'—diluting harmful materials which cause particular symptoms in order to cure those symptoms instead."

"[i]Extremely[/i] diluted materials, to the point where there's not a single molecule of the original substance left." Riggs grinned. "You might say, literally water."

"Huh. So he's, what…" Tanner trailed off.

"Trying it the [i]other[/i] way, we think." Riggs leaned back in her chair. "Diluting something which normally heals, to slowly poison our Financial Services head over time. Three weeks ago, he bought a bottle of antivenom online."

Tanner laughed incredulously. "Wait, you weren't kidding? He's actually trying to murder her?"

Riggs laughed back. "Harmlessly and entertainingly."

"Still," Tanner said, "shouldn't we be arresting him before he decides it's not working and tries something else?"

"And get chewed out by Queen Bitch for sacking the longest-lasting assistant she's ever hired?" Riggs asked. "Besides, what's he going to get through security?"