Oh, Orphan Black, you are a harsh mistress. You make me care about these characters, and then you screw me over with the plot.
The end of season two featured a striking example of what I call the old Arlington Road Trick, which features prominently in that Jeff Bridges conspiracy thriller movie. The Arlington Road Trick occurs when a bad guy leaves a piece of false information around for a good guy to find and be misled by, while leading the good guy to believe that she'd only discovered it by happenstance.
It requires a very specific level of concealment to hide something well enough that the good guy won't suspect it's a plant, while simultaneously having it conspicuous enough that there's no chance the good guy will overlook it. Note again that the only reason for concealment is to establish the false information's bona fides - making the good guy believe the info could only have come by happenstance, that it couldn't have been planted.
But that's not all. The bad guy's plot also depends on knowing exactly how the good guy will react to the discovery. Will she call the person who needs to know? No. Will she go and tell it in person? No. She will drive to the building the person is in, send in a message, and have them come out to the car. Otherwise the bad guy's plot won't work.
For extra added bonus, the bad guy has to get to the same building before the good guy does, execute a meticulous change of costume, and know someone she's barely met better than two people who've known her all her life.
The common thread in all of this is that the reason the various good guys - four of them in this instance - and the audience never suspect a trick is that the trick would, in fact, be impossible to pull off. Or, at least, to be sure you could pull it off - and, if it failed, it would be disastrous to the plotter.
I was less disturbed by the gratuitous introduction of a new clone character who makes no discernable contribution to the plot, for the sole purpose of throwing an even tougher acting curveball than ever before at Tatiana Maslany, because her acting skills are just awesome and deserve this showcase. And an Emmy, which in her case she has not got.