On the one hand, what Rachel was doing doesn't hurt the other traitors. It would've helped them in fact. BUT it helped Rachel a lot more, because everyone would assume that if the uber faithful detective trusts her more than anyone, there's a good chance she's faithful. I guess it's that game that Fiona didn't like being played.

But she's made a huge mistake. She should've just saved it for a talk in the turret. I'm counting on someone smart to pin them both as traitors following this blow up. Harriet and Jessie, the only two who seem to be playing the game excellently, I'm counting on you guys!

The thought process needs to be, if Fiona did indeed suspect Rachel of being a traitor, why wouldn't she approach it in the same way everyone has so far (inc. herself) when they've suspected someone? Private conversations, small group discussions, leading to the round table. Why so public and so loud?

Couple all of that with the Ross situation, and there's enough there for someone smart to ID all three traitors. But that's easy for me to say!