AMC's (AMCX -1.48%) The Walking Dead continued its hot streak on March 16 with "The Grove," which attracted 12.9 million total viewers and a 6.4 rating among 18 to 49 year olds. The 14th episode of the fourth season was a slight improvement from the 13th episode, "Alone," which attracted 12.7 million viewers and a rating of 6.3 among 18 to 49 year olds.

The Walking Dead has loomed large in headlines this season, especially after topping the Winter Olympics on Comcast's (NASDAQ: CMCSA) NBC network among 18 to 49 year olds for three consecutive weeks in February. The show eventually lost to the Oscars on Disney's (NYSE: DIS) ABC at the beginning of March, but that challenge only caused The Walking Dead's viewership and demographic rating to dip 3% from the prior week.

Carol and Lizzie. (Source: AMC Press Center)

With tough competition such as the Olympics and Oscars now out of the way, The Walking Dead could easily surge into its season finale on March 30 on a season and series high. Although most viewers now clearly know what a ratings juggernaut The Walking Dead is, we should also discuss the new pace of the show and its departure from its comic book roots.

(Be advised that there are spoilers ahead, so you might want to return to this article after you're caught up with the most recent episodes.)

Of Mice and Men and parallel universes
"The Grove" ranks among the most shocking and disturbing of The Walking Dead's episodes so far. It was also one of the most strongly acted and thought-provoking ones, and finally gave Melissa McBride (Carol) and Chad Coleman (Tyreese) a rare chance to flesh out their characters.

Writer and showrunner Scott Gimple and director Michael Satrazemis cleverly masked their true intentions for the two sisters, Lizzie and Mika Samuels, until the last act of the episode. Although the audience was already aware that Lizzie was mentally unstable, nobody, not even the readers of the comic book, expected her to kill her sister to change her into a walker.

It all ended on a darkly poetic note. Carol's response -- to tell Lizzie to "look at the flowers" before she shoots her -- was a thinly veiled reference to Steinbeck's Of Mice and Men.

Carol shoots Lizzie. (Source: AMC Press Center)

In a previous article, I pointed out that the show's writers were intentionally constructing a parallel TV universe to the comics, in which dead characters in the comic stay alive while living characters die. Some characters even die in ways meant for other characters -- for example, it was Tyreese, not Hershel, who was supposed to be beheaded by the Governor. All of these changes and tweaks keep the show fresh, even for longtime fans of the comic.

The deaths of Lizzie and Mika are perfect examples of how the writers have cleverly altered familiar storylines from the comics. Lizzie and Mika didn't exist in the comics, but their story is nearly identical to the tale of two brothers in the comic, Billy and Ben. Ben killed Billy in the same way that Lizzie kills Mika, and he was subsequently killed by Carl Grimes.

Yet turning the two boys into young girls in the show, then having their adoptive mother Carol execute Lizzie feels twice as cruel as the original story. However, the dramatic impact resonated much more strongly than the original comic book plot.

Two roads diverged in the grove
Since the writers have made it clear that the show takes place in a different parallel universe as the comics, we should discuss the intriguing new questions presented by the show.

Fans of the comic know that Carol and Tyreese were romantically involved in the earlier issues. However, the comic book version of Carol is drastically different from her TV counterpart. Carol's "battered wife to warrior woman" transition seen in the show never happened in the comics.

"The Grove" is the first time that the two characters have spent a large amount of time alone together, and even though Carol killed Tyreese's girlfriend, it lays the groundwork for the two characters to grow closer together.

Meanwhile, the various scattered characters are continuing toward Terminus, a brand new location that didn't exist in the comics. This will inevitably be where the fourth season concludes, and fans of the comic are probably wondering if this means that the writers intend to explore a brand new area exclusive to the show. Moreover, the season finale could be a setup for The Walking Dead spin-off, which is scheduled to premiere in 2015.

How much longer will The Walking Dead keep on walking?
Considering that The Walking Dead's ratings have surged every season, from an average of 5.24 million viewers in the first season to a range between 12 million to 16 million during the fourth, it's safe to say that AMC will keep the show on the air for as long as possible. The show was already renewed for a fifth season last October.

The Walking Dead continues to be a top contributor to AMC's top line. AMC's advertising revenue jumped 26.7% year-over-year to $663 million in fiscal 2013, thanks to robust support from shows like The Walking Dead, Breaking Bad, and Mad Men. However, Breaking Bad concluded last September, and Mad Men is scheduled to end in Spring 2015. This means that there's a lot riding on The Walking Dead, its companion show The Talking Dead, and the upcoming Walking Dead spin-off until AMC can launch its next hit show.

(Source: AMC Press Center)