Those who watched The Walking Dead midseason finale on AMC last night likely noticed a mysterious 30-second TV spot that had no title attached, featuring hordes of rats near a sewer gate. The video has been identified as a promo for FX's upcoming series The Strain, based on Guillermo del Toro and Chuck Hogan's novel trilogy. If you look very closely, the words "He is here" are flashed on the screen during this viral teaser, a phrase which was used often in the books. The novels also feature a scene where rats escape from the sewers...

We reported last month that The Strain debuts July 2014 on FX, so stay tuned for more videos from the series.