It centered on a man-made chimera, which escaped from an animal testing facility and attacked various people, including Agent Charlie Francis, while the Fringe team tries to stop it.

The Fringe team consisting of FBI agents Olivia Dunham (Anna Torv), Charlie Francis (Kirk Acevedo), Philip Broyles (Lance Reddick), and civilian consultants Peter (Joshua Jackson) and Walter Bishop (John Noble) arrives, and Walter sees evidence of different creatures' marks on the bodies.

While investigating the animal control team deaths, Charlie is attacked by the creature, but it fails to kill him after Olivia arrives on the scene.

Though initially thinking Charlie was healthy after the attack, they realize the chimera's stinger injected him with its larvae, and that he has less than 24 hours to live.

Olivia learns one of the victims, Jonathan Swift, was the son of a scientist who tests on animals, and was killed while breaking into his father's lab.

He and Peter carry 50 caliber Desert Eagle handguns, called "monster killers" by one prop crew member.

So then they pour these worms and this goopy, syrupy stuff and this fake blood onto this guy’s chest... We had to zip him up in the body bag.

"[9] New Media consultant Glen Whitman stated in an interview that this particular episode contains some recent scientific developments that were part of their inspiration for the creation of Fringe in the first place.

Whitman concluded that they were partly inspired by scientists Osamu Shimomura, Martin Chalfie, and Roger Y. Tsien and their work on research on isolating genes from jellyfish for the treatment of Huntington's disease; all three won the 2008 Nobel Prize in Chemistry.

[11] Ramsey Isler from IGN rated it 7.8/10, explaining the "mysterious escaped monster" is a tired idea that failed to bring anything new to the show, and the episode "lacked real suspense and intrigue".

[12] Josie Kafka of Open Salon.com saw allusions in the episode to many other genres, including Buffy the Vampire Slayer, Halloween, and Dollhouse.

[1] Sarah Stegall from SFScope was skeptical of the chimera premise, but wrote she was willing to overlook that because the episode "delivers [entertainment] in spades" and gives "a fine payoff...

There are creepy sewers, pee jokes, heroics, tears, laughter, scares, and finally a kill shot of a terrifically scary monster".

[2] Andrew Hanson from the Los Angeles Times praised the episode, writing the writers and characters were "finally getting into their groove," and that the monster sequence was "better than most horror films I’ve seen lately".