Whatever is infecting the population on The Walking Dead seems to be spreading.
The popular AMC zombie show's returned Sunday night from its third season break to a remarkable 12.3 million viewers, a series high for the show, according to Nielsen ratings.
Sunday's episode is now the highest rated telecast ever for a basic cable series. Including encore airings, 16.6 million people tuned in to watch "The Suicide King," the ninth episode of the 16-episode season.
Even going up against the Grammys, the mid-season premier grabbed 7.7 million adults in that prime target demographic of adults ages 18-49. The show's previous record was 10.9 million, for the Season 3 premiere back in October.
The season finale will air March 31.
The Walking Dead received an early Season 4 renewal, which is expected in October.