Damn, only two episodes left before the inevitable cancellation. As much as fans want to believe their show can come back for another season, don't waste time; the ratings for Terriers are pathetic, a mere 0.2 adults 18-49 for most of the season, and it's on FX, a thriving network which doesn't need the show.
"Sins of the Past" sets up the backstory for Britt and Hank, and half the episode or possibly more is dedicated to a case three years ago in which Hank crossed paths with Britt. At the same time, we see the breakdown in Hank's marriage.
Terriers is a show that is largely based on coincidences--Hank and Britt stumble upon cases at random times during the day--so it's fitting that there is a parallel drawn between the case three years ago and the continuation in the present. The case three years ago, in which Hank tried to bring down a rich guy for rape, appears be the beginning of the end, when he loses both his job and wife. In the process, he meets Britt who's a good guy overall. In the present, Gustafson and Hank catch the real rapist, a fellow detective, with the help of the rich guy. While that's going on Britt tracks down Katie's friend from class--not the professor who slept with Katie--and beats him to a pulp. In both Hank's case three years ago and Britt's beating in the present, they're blinded by rage and alcohol and miss the real culprit.
At the end of the episode, Hank tells Britt that Katie told him about the incident and expectedly, Britt blows up. There isn't a right or wrong person in this situation. We can point fingers at Hank, Britt, Katie, but in the end, everyone's at fault in some way. It's hard not to feel bad for them. Things just can't fall in their direction.
Score: 9.2/10
