"Andy needs me," she says, when Greg asks her why she's staying on, unpaid - or at least, that's what we assume, in the absence of any other explanation.
"Why does he need you?" says Greg.
Vicky's continuing presence has obviously wiped out his few remaining good manners.
"Because I'm the only one he trusts," says Vicky - which just goes to show that Andrew's judgement has completely gone to pot, as far as I'm concerned.
As a result, office morale is at an all-time low by lunchtime and then, to make matters worse, Mr Sampson phones to ask how his (very long-standing) case is going.
"Mr Sinclair said he'd send me something in the post quite urgently," he says. "But nothing has arrived yet."
"Oh," I say. "I don't know what's happened, I'm afraid. I didn't know there had been any new developments, and there are no recent updates on the computer. When did he tell you this?"
"When he visited me. The week before last, I think it was," says Mr Sampson.
"Ah, yes. I was off sick that week, so that's probably why I wasn't aware of it. Just hang on one moment, and I'll get your file."
I put Mr Sampson's call on hold, and head for the filing cabinet. I look through it twice, then on my desk - but there's no sign of the file. I promise to phone Mr S back, and search again, still without success. I'm rifling through the paperwork on Greg's desk when he walks in and asks what the hell I'm doing.
"Trying to find Mr Sampson's file," I say. "Can't see it anywhere. Have you had it?"
"No," says Greg. "Andrew took it with him when he went to visit Mr S. I'll phone and find out what he did with it."
"He took Vicky with him? To see a constituent?"
"Um, yes. I didn't like to tell you that bit."
Oh, for f*cksake. And it doesn't get any better. When Vicky finally returns from lunch, she claims that she left the file on my desk. She doesn't blink while she says this, and then comes the worst news of all.
"It was so that you could do that photocopying," she says, while smirking. Fishily.
"The constituent gave Andy a pile of documents to take copies of. Then he was supposed to return them by post."
I look at Greg, who looks back at me. Neither of us wants to ask the next question but, as usual, I cave in first.
"Vicky, please tell me that these aren't original documents we're talking about?" I say.
"Oh, I should think so," she says. "Otherwise the constituent wouldn't be so anxious to get them back. You don't want any Tom, Dick or Harry laying their hands on the deeds to your house, now do you?"
Does she have to look as if she's enjoying this quite so much? Honestly, sometimes I can quite understand what motivates axe-murderers. Especially serial ones.
I could cheerfully kill The Boss as well as Vicky. Although she might be first on today's list of people that I plan to do away with come the revolution, Andrew's a close second. Especially after I call him with an update.
"Well, Molly - you'll just have to phone Mr Sampson back, explain that you've lost his file and apologise," he says.
"Me?" I say. "I wasn't even at work when you - or Vicky - managed to mislay the damned thing. Containing really important, original documents, for God's sake."
"Collective responsibility's the thing," he says, before he hangs up on me. Now it's my turn to make V signs. Mine are even more extravagant than Greg's.
There's no getting away from the fact that a holding manoeuvre is needed, though. I phone Mr Sampson and tell him that the file is still in Andrew's briefcase, which he's taken to London with him - so I'll have to get the paperwork sent back from there. (I really hope there's no bad Karma for white lies, or I am completely buggered in the next life.)
I'm clinging to the hope that we'll find the file and solve the whole problem, but it's already almost 7:00pm and Greg and I are still searching the office, while old fish-face is long gone. She's probably washing all her hair tonight, or doing something equally important, whereas Greg and I won't be going home until we've found what we're looking for.
There's paper everywhere and the place already looks as if it's been ransacked. We haven't even had time to discuss what on earth we're going to do about the most serious problem: Vicky. I don't know why, but I've got a horrible feeling that she lost this file on purpose. It might pay not to underestimate hair-flickers in future, especially as I can't get the image of a smiling piranha out of my head. Or the sound of a very familiar tune.