Bird Box Barcelona is a spin-off of the Netflix original and expands upon the world while focusing on a different slate of characters surviving the apocalyptic world in the titular city.
When the world is attacked by mysterious invisible creatures who alter the minds of those who see them, humanity is decimated. Bird Box Barcelona follows a man named Sebastian and his daughter Anna trying to survive in the post-apocalyptic world.
In a shocking twist in the beginning, Bird Box Barcelona reveals that Sebastian survived seeing the creatures and turned into one of the people the film later on terms “Seers.”
To see or not to see
An inexplicable global attack on humanity sees invisible, mysterious creatures manipulate humans most diabolically. Their victims can be put into two categories.
The first one includes all humans who look at the creatures, go through an incredible change psychologically, and are instantly manipulated by this effect into committing suicide.
The second one includes people who look at the creatures but do not become suicidal. Instead, they live on, only to be constantly manipulated by the mysterious beings into doing their bidding.
They become mad and devoted to the service of these creatures. Most of them consider and hail the creatures as divine entities, as per their pre-existing faiths and beliefs.
These people commit treachery, deceit, and just about anything to make other survivors open their eyes and look at the creatures. Bird Box Barcelona terms these people as Seers.
Immunity through trauma
There is something different inside the brain of seers that sets them apart from the other survivors, which also enables them to live on even after having seen the creatures.
This little difference makes them immune to the suicidal tendencies that a simple glance at the creatures inspires in all the other survivors. While Bird Box reserves explaining what this difference is, the spinoff offers a plausible theory.
At the end of the film, Claire arrives at the camp that has been set up at the Montjuïc Castle, offering the survivors a safe haven while the Military force there also runs experiments on Seers, mice, and even a creature locked up inside a containment room.
One of these officers who collects Claire’s blood to run tests on it explains that they’re looking for a possible chemical marker in the blood. This essentially means that they’re looking for signs of trauma, which is extremely common in the Seers.
The explanation is that an epigenetic alteration of the DNA makes a human somehow immune to the suicidal effects brought forth by looking at the creatures. They think that a key to immunity against the creatures may lie in the DNA of the Seers.
Before Bird Box Barcelona rolls the credits, the officers and researchers at the Castle are shown to be conducting an experiment wherein a mouse injected with the DNA of a Seer is exposed to a creature inside the containment room.
By the looks of it, they have been making progress with their experiments, and test subjects are able to live longer and longer before succumbing to the effects of the creatures.