This season has continued to entertain with excellent scripts and excellent acting. The only two implausible episodes were those that dealt with the "undercover" situation. (No spoilers).
Otherwise, seasons 3 & 4 are consistently top notch. It's great that "old favorites" return and you really get a sense of the ebb and flow of this police department. it's still very interesting to me the way we rarely get any backstory on any of the characters and when a little is revealed it's rarely ever followed up. Yet this doesn't detract from the overall enjoyment of the show because we come to expect this. Any tiny insight into their personal lives is a real treat in an episode and we don't expect to hear anymore about it in future episodes. Being able to binge watch so many episodes in a row, as I have done, is a real testament to the quality and like ability of the scripts and the whole show.
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