Abbie Carmichael made a very strong first impression when she was first introduced, and throughout her stint on 'Law and Order' she continued to be very interesting in personality, her approach to cases and her views. Of all of McCoy's assistants, she has always been my personal favourite (Southerlyn was the only one who never did it for me). "Agony" has always been one of her meatiest episodes, in terms of character writing and from a dramatic standpoint.
Season 9 at its best was outstanding and its first half was certainly of a solid standard. One of the best episodes of the season (and an earlier seasons high-point) is "Agony", a character and dramatic showcase for Carmichael and where she really comes into her own. It is one of her best episodes and is worth it for Angie Harmon, a very memorable guest turn and the ending primarily. Though everything about "Agony" works absolutely wonderfully.
Photography and such as usual are fully professional, the slickness still remaining. The music is used sparingly and is haunting and non-overwrought when it is used, and it's mainly used when a crucial revelation or plot development is revealed. The direction has nice and at its best (such as towards and at the end) thrilling tension while keeping things steady, without going too far the other way.
On the writing front, "Agony" couldn't be better. The script is scary in its intensity later on and always probes thought. The final confrontation especially is brilliantly written and one of the season's best scenes in terms of writing and the character interaction. What also stands out is the whole debating on the issues raised here, where one sees what stance the characters take on them. For instance we know that McCoy is pro-death penalty, while it is established early on that another assistant of his disagrees and in a way where one can understand both sides.
The story is suspenseful and has plenty to keep one guessing, nothing is obvious and one is suitably challenged while not being confused by what's going on. All the conflict surrounding building a case on limited evidence and the quest to find more (a familiar trope but expertly and intriguingly done) keeps one on the edge of the seat. The final confrontation stands out though.
Carmichael comes into her own here as said and "Agony" has one of the scariest perpetrators in a while, where it is easy to root for them to be convicted and get an at least a life without parole sentence. Angie Harmon is particularly good of the regular principals and Christopher Patrick Mullen also plays his part perfectly.
In conclusion, brilliant. 10/10.