The Square Root of Murder (Professor Sophie Knowles)

but mostly to have company in the store, if only in the form of a friendly voice.
    I waited while the phone dialed. Or whatever these smartphones did.
    Hal would know. Besides being a physicist, Hal was a techie and tutored everyone in Franklin on our latest i-purchases, doing a much better job than the manuals that accompanied them. I cheered myself with the fact that Hal’s ruse would soon be revealed and Timmy would have his father back, if not his mother.
    I walked toward the new beaded curtain that led to the back room where I’d last seen Ariana’s binder.
    I stepped over the threshold and into a loud noise.
    Crash!
    Gillian Bartholomew had smashed the window and entered the shop by the back window, the better to avoid being seen, I imagined. Even in my shock, I had to admire her agility as she climbed over the low sill.
    My heart seemed to stop; my throat tightened to the maximum as I pretended not to scan her body for signs of a weapon. Both her hands were visible and empty, but she was wearing a khaki fisherman’s vest with many pockets. It couldn’t have been for warmth, so I imagined the worst. A knife in the top right pocket, a gun in the lower right, a venomous needle in the lower left, and a bomb strapped across her chest.
    I hoped I was wrong and she was packing only lipstick and tissues, like a normal woman.
    I slipped my phone into my own pocket, ruefully empty of weapons. I didn’t have “speaker” selected and couldn’t tell if Bruce had picked up or if it had gone to his voicemail.
    “Gil,” I said, loudly, in case Bruce was listening. “What are you doing here?”
    As if I didn’t know.
    It didn’t surprise me that “breaking and entering gracefully” might be part of an army reserve soldier’s skill set.
    “Why, Sophie, why?” Gil asked, a sad look on her face.
    Wasn’t that a more appropriate question from me to her? Not the time for technicalities, however.
    Gil had a good four inches on me, and more than a few pounds. Moreover, she’d spent her life building up strength in physically demanding jobs, whereas, except for the occasional bike ride and kicking the exercise ball out of my way in the garage, the most athletic thing I’d done this summer was sharpening my puzzle pencils.
    It was lighter in this area since the back window had no shades, and now, no glass either. I thought of running to the window and waving and screaming madly for help, but Gil was between me and the window, and the alley seemed deserted anyway. I could turn and run out through the sales floor, but I had a feeling she was quicker than I was. Wrong or not, I envisioned emergency workers like Gil able to run at the speed of light.
    I saw that Gil’s eyes were tear streaked, her face a map of despair. She inserted her hand into one of the vest pockets. I clutched at my shirt and swallowed audibly. She pulled out a tissue and wiped her eyes. I relaxed. Sort of.
    “We should talk, Gil,” I said.
    Good luck with that , I added to myself.
    Gil shifted from one leg to the other, nearly hopping off the floor. “The funny thing is I knew I blew it, going back, moving the cake inside, adding those thesis pages. Overkill.” Poor word choice, I thought. “But when I saw that Rachel was going up to his office”—this came out as a hiss—“I couldn’t resist. I knew I should leave well enough alone but I wanted to be sure the little tart was suspect number one.”
    “Tart? You think Rachel and Hal—”
    Gil stopped hopping and began rocking on the heels of her heavy athletic shoes. She seemed to be warming up for . . . I didn’t want to think what.
    “It doesn’t matter if they did or they didn’t. Rachel wanted it and Hal’s weak. God, is he weak. He took it on the chin for years from the great Dr. Appleton. The slights, the public insults, and then the letter, the final straw.”
    Except for Gil’s deranged look and the smashed window, a passerby might have thought she was witnessing two girlfriends talking things over, albeit one more agitated than the other.
    I began to relax. Maybe Gil actually had come to talk. She hadn’t threatened me physically. Yet. I checked the alley for a dark sedan, but the broken window was too narrow to provide much of a view from where I stood. Most likely she’d followed me here from campus, or she might have been on my tail all day for that matter.
    Ergo, I reasoned, if she’d wanted to do me harm she’d have taken one of a wealth of other