Inside the enigmatic Enclave facility, Dr. Siggi Wilzig, a brilliant scientist, delves into the creation of an unearthly blue substance. With a determined eye, he injects the mysterious concoction into his neck, feeling its foreign power surge through his veins. However, his clandestine experiment is soon exposed when he is caught harboring the experimental dog, CX404, in secret.
In the aftermath of this discovery, Wilzig is forced to flee the confines of the facility, leaving behind a trail of chaos and confusion. Meanwhile, Lucy's path crosses with the fugitive scientist, who urgently implores her to return to the Vault 33. Obliging to his request, she embarks on a perilous journey.
As Maximus and Titus embark on their own search, they are suddenly attacked by a mutant beast, leaving Titus severely injured. In the heat of the moment, Titus lashes out at Maximus, accusing him of failing to protect him. Enraged, Maximus allows his companion to bleed out, seizing his powerful armor as his own.
Lucy finds herself in the quaint town of Filly, where she reunites with Wilzig, who is desperately trying to arrange a safe passage to Moldaver. However, their escape is abruptly interrupted by the unexpected ambush of Howard, who is hell-bent on capturing Wilzig for his bounty. But just when all seems lost, Maximus intervenes, saving them from Howard's clutches.
In the chaos, the wounded CX404 is left behind, but Howard, showing a surprising amount of cunning, nurses the dog back to health and uses him to track down Lucy and Wilzig. Desperate and knowing his fate is sealed, Wilzig ingests cyanide, offering Lucy a grisly yet pragmatic solution: carrying only his head would increase her chances of reaching Moldaver alive.
