This is arguably the bleakest season so far. Although the writing, performances, and production value have remained consistent since the show's debut, "Spook Street" felt slightly uneven and, at times, undercooked and anticlimactic, particularly in how the storylines unfold. Things have also turned more and more implausible each season, particularly in the ways the Slow Horses become involved in the events. Particularly repetitive is also the role of MI5 behind the curtains. Nevertheless, the show remains solid enough to satisfy fans of the series, providing particularly intense moments centered around its main cast.

I rated this season a 5, although it's closer to a 4 than a 6. This show quickly became a bad parody of itself. This was a poorly written and executed season. It's become a bad slapstick comedy. The first season was nice (despite it's poor foundation), the second season was fine (despite several bad moments) and the third was an improvement over the second. This season annoyed. It's flat out bad. Three unnecessary chalk outlines of characters were added, but none were introduced, explained or explored. The season contained unbaked hints of several confusing and melodramatic stories, but none were managed or told well. The department of lost misfits has apparently become the focal point of law and order. Not only do none of the characters experience any meaningful growth, it could be argued that all of them regress to the point of caricature. I could go on and on, but if the showrunners can't be bothered, why should I? Like the weakest episode of season 2, the ratings for this season were higher across the board, despite the significant drop in quality. This is one reason why we can't have nice things. If writers are unable to develop a quality story, they should end the show or take the time needed to make it good. Content is king. Even with the story they had, it could've been better. A surprising drop in quality. I was hoping elements of season 3 were wrinkles that would be ironed out. What happened? Edit: I changed the rating from 5 to 4. My positive feelings about the first 3 seasons unduly influenced my thoughts on a surprisingly bad left turn.

I think the breaking point for me was when someone who's supposed to be an agent shoots someone at point blank multiple times and misses because the target languidly moves behind a car door. The story this season was REAL bad. Somehow 6 episodes feel stretched out cause the plot is paper thin. The subplot with Marcus selling a gun was completely unnecessary and added literally nothing. Neither of the two new characters in Slough House added anything and the usual suspects, Ho and Shirley are worse than ever. The main plotline was dogshit. Yet another season with an "MI5 did stupid shit in the past and it comes back to haunt everyone with Slough House forced to pick up the pieces" theme. Can we please be done with this already? And ANOTHER bomb? If they do this yet again with S5 I'm done. They're wringing this towel drier than the Sahara. What a waste of power houses like Hugo Weaving and Gary Oldman good god.

I'd reiterate the comments by manicure. Season takes a while to kick into gear and even then it isn't as good as last season. Shame. Fine enough to pass the time but a let-down overall.

It’s a fourth season, so I guess it’s normal, but for quite a stretch this felt a bit samey, with no big surprises or new stuff, just the usual well-made thing. Which, again, is perfectly normal and also is fine, considering how much I like the show. But the two final episodes are amazingly good and left me smiling and craving for season five so I guess I can’t complain.