The episode followed the Fringe team's investigation into horrible deaths caused by large parasitic worms erupting from their victims' mouths.

Andrew Orloff, the episode's visual effects supervisor, strived to makes the parasitic worms look as real as possible with the help of the actors and camera angles.

In Dorchester, a damaged cargo ship from China washes ashore; all of the crew members seem to be infected with squid-like creatures which soon erupt from their mouths, effectively killing their hosts.

While investigating the crime scene shore, the Fringe team discover a healthy young Chinese woman, who tells them all of the passengers but her were given pills for their perceived seasickness, and that another ship is expected in two days.

While at her house, Peter (Joshua Jackson) observes signs of obsessive compulsive and germaphobe characteristics such as large quantities of hand sanitizer.

These two discoveries lead Peter and Olivia (Anna Torv) back to Jarvis' house, and they learn that her son (Colby Paul) has an immunodeficiency disorder.

So we're transferring not just the camera motion but also the performance of the actors on set onto 3D pieces of geometry so we can deform them and warp them and have our effects interact with them because the mandate is all about making it look as natural as possible, so that means a lot of optical tricks and atmosphere put in as seamlessly as possible.

[5] Fringe aired against repeats of Grey's Anatomy and CSI: Crime Scene Investigation, helping the series earn a 25 percent ratings increase since the season premiere.

[9] Writing for the magazine New York, critic Tim Grierson called the focus on Walter the episode's best moments, but wrote that after the audience "adjusted to the ew factor, the plot wasn't all that interesting.

The story line about rich, ailing Americans paying Chinese gangsters for miracle cures appeared to be a ripped-from-the-headlines commentary on hot-button issues like human trafficking and illegal immigration, but the execution just seemed silly.

[2] Though not appearing as depicted, the species is a real-world hookworm that infects a large number of Earth's population, which as said in the episode, has been used by some as an alternative treatment for asthma and other allergies.

[14] A George Washington University Medical School doctor noted that some scientists are researching the healing potential of parasitic worms.