We've already seen and advance screening of Sunday night's "Isolation" episode of The Walking Dead, but we're not allowed to tell you any spoilers from the episode until after it airs, which is a good thing. There are a lot of theories out there about what may have happened at the end of last week's episode. They are all wrong. If you're a Walking Dead fan, then you owe it to yourself to watch this one live. The "Isolation" episode is the best written episode of Season 4 so far. It was written by series creator Robert Kirkman. Kirkman delivers a masterful script on par with the storylines you would find in some of best crime dramas on television. Everything logically builds to the shocking ending that you always know is coming on Walking Dead, but still can't help feeling caught a little off guard by. Besides Kirkman's incredible script, perfectly executed by director Dan Sackheim and showrunner Scott Gimple, the other reason this episode is so good is that two cast members really shine in their performances. As probably expected given last week's ending, one of the cast members is Chad L. Coleman. In Season 4 so far, Tyreese has been kind of the tag-along, whiner of the group. That changes this week. We finally get to see the Tyreese that fans have been waiting for. We finally see the caliber of acting that Coleman is able to deliver on the show. Tyreese finally becomes a character we're actually interested in seeing what happens next with. The other cast member that shines is Melissa McBride. Despite being around since Season 1, Carol has always sort of operated in the background of the group. However, in season 4, Carol has been emerging as a more active player. That trend continues this week. With "Isolation," McBride delivers her best performance on the series to date. "Isolation" also contains a scene that is sure to thrill fans of the comic book, as well as action fans in general. While "Isolation" at its heart is one of the most thought-provoking episodes, it also contains a "jump-up-and-down" in excitement action scene. As we said before, Tyreese has finally arrived on The Walking Dead. "Isolation" is a riveting, well-thought out episode. It's got an Emmy-worthy script and Emmy-worthy performances. If the remaining episodes of Season 4 are as good as "Isolation," then this truly might be the best season yet of The Walking Dead.