The episode follows the Fringe team's investigation into horrible deaths caused by large parasitic worms erupting from their victims' mouths. The case soon leads them to a Chinese gang and a black market of immunodeficiency medicinal drugs.
This episode's glyphs spell:
The Observer can be seen crossing the foreground in Chinatown as the Triad member is phoned with instructions to follow Astrid.
At the motel in 'August' where Christine Hollis is being kept, August brings Christine Hollis a meal in a paper bag with a Chinese dragon drawn on it while Christine is being kept hidden in a motel, foreshadowing the villains working in Chinatown in 'Snakehead'.
Signage in Chinatown in 'Snakehead' says "Ginseng Improves Memory!", foreshadowing the plot of 'Grey Matters' where pieces of Walter's brain are recovered to help restore his memories.