It hadn't occurred to me until this episode that Stargate SG-1 actually does drama really well. I mean, I do enjoy the show when it's in "fun action runaround" mode, but I definitely like it the best when the episodes are on the more dramatic, character-based side (Solitudes, Singularity, There But For the Grace of God, Point of View, Forever in a Day, Jolinar's Memories/The Devil You Know, The Serpent's Venom, 2010). I suppose that's why I sometimes get frustrated with SG-1 because it tends to focus more on the action when I might be after something meatier - it's a show that really, really depends on my mood. This is a series that fits the bill perfectly when I want something a bit lighter or just plain fun to watch, but that isn't always enough. Thankfully it usually delivers when I want it too and it very much did here.
Anyway. Threshold. This episode made me cry at the end. I don't think this series has managed that before, although the sensitive examination of grief that was Forever in a Day came very close. I love that this episode finally showed us just what makes Teal'c tick - it's only been five years, but they got there in the end! We finally get his reasoning for switching sides in Children of the Gods explained. We get to see how he came to realise Apophis and the Goa'uld were false gods. Threshold is essentially a very, very well done flashback episode, interspersed with some tense scenes where the rest of SG-1 and Bra'tac are forced to confront their brainwashed friend and bring his old self back again. It's amazingly acted (especially Tony Amendola, whose episode it is almost as much as Christopher Judge's), brilliantly written (Brad Wright can really bring it when he wants to) and superbly directed, with some really memorable visuals (the snowy plains, Ra's ruined planet).
One of the very best episodes of the series and a fine addition to a very strong overall season.