A highway construction worker in rural Pennsylvania goes missing when he is mysteriously drawn into an underground tunnel filled with human remains. Meanwhile, back in the lab, Walter is attempting to simulate travel between realities on frogs. When it's discovered that the disappearance in Pennsylvania is not an isolated incident, the Fringe team travels to the crime scene to unearth evidence.
Synopsis provided by the Fandom Wiki, Fringepedia, and Wikipedia.
This episode's glyphs spell: M-I-R-R-O-R
Certain events in this episode mirror the struggles Walter is going through in his personal life, such as the line "The grave of a boy... who was not in his grave", a reference to Walter visiting the grave of Peter Bishop in the season 1 finale. Alternatively, "mirror" could be a reference to the Shapeshifters in the previous episode who could mirror their look after anyone else.
FRINGE DIVISION CASE FILE #202-92409
FRINGE EVENT: Genetically engineered super-baby
CLASSIFIED CASE CONNECTION(S): N/A
AGENTS ASSIGNED: Dunham, Francis, Jessup
SUPERVISING AGENT: Broyles
FILE ARCHIVED BY: Rosangela Torres da Silva
WITNESSES/CONTACTS: Dr. Andre Hughes (suspect; deceased), 7 townspeople
LOCATION: Lansdale, PA
VICTIM(S): Raymond [redacted], Sheriff Golightly, Hughes' offspring
CASE REPORT SUMMARY:
In Lansdale, Pennsylvania, six people were reported missing in two months, four of whom eyewitnesses said had disappeared into thin air. Investigation led to the discovery that resident Dr. Andre Hughes did research in reproductive biology and gene replacement. It was thought his wife and child had died seventeen years ago. The recent disappearances connected to a mutated creature that secreted a paralytic substance containing male human DNA. An exhumation order for Dr. Hughes's family was processed, and Eveline Hughes was found to have had a very advanced case of systemic lupus erythematosus, making it impossible to give birth to their child. Dr. Hughes altered their fetus with possibly mole-rat and/or scorpion DNA so that their child could survive its mother's lupus. The creature was kept alive by Dr. Hughes until his secret was discovered.