I wouldn't say it was my least favourite episode of Season 5, but it wasn't that great. I think a lot of why I didn't like it had to do with the pacing of it - with everything they just crammed into this one episode, I feel like I didn't get the full impact of the things I was supposed to get. The thing is, I think the first confrontation was supposed to be a flashback (that's the one where Stella was told she was being put on desk assignment?). Which is why they should've put it in an earlier episode, so we could've gotten a better sense of how tense things were between Stella and Mac. Maybe it should've gone at the end of Greater Good, or Yarzheit. I don't think NYPD has voiceprint analysis, nor do I think Stella made the call from her mobile...but it's entirely likely that Mac (since he was running the investigation) went over to NYPD Communications to listen to the informant's call (since presumably, said informant wasn't at the scene when Diakos was found). And then he recognized Stella's voice. I think the Stella/Mac conflict and resolution was glossed over because of everything else they were trying to fit into this episode. Again with the pacing. What with trying to highlight how strong Stella's relationship with the Professor was, and the artifact-smuggling ring, plus Stella/Mac, it kind of turned into this huge jumbled mess. I think Stella's "thank you" would've gone over better had we actually seen her making things difficult for Mac and the department. Like if we'd seen her being pulled off cases in earlier episodes, or assigned to a desk while everyone else worked. Had they spaced out both Mac and Stella's rift and Stella's relationship with the Professor (we should've at least gotten more than the little bit we had in Point of No Return), then I think the impact of Stella and Mac's resolution would've meant more. As would the fact that the Professor took a bullet for Stella (which was sweet, but I didn't care as much as I think I should have, mostly because we barely knew who this Professor was, let alone his relation to Stella).