This is a show thst should have quit while it's ahead. After several years, I went back and watched the series again. Without doubt, it hasn't aged well. This surprises me. Also, season 4 is just awful as is the Abominable Bride. The show went from being interesting and entertaining to a political soap opera. It went off a cliff edge in season 4 and the absurd Mary story. This failed to stay true to s1-s3. If you're watching this for the first time or revisiting the show, stop with s3. I truly hope they bury thus series. It ran its course and then some.