Alien Species

"Its the perfect system, why invade when you can convert the planet into you" Ramsey describing the aliens method

The Threshold aliens are the unseen masterminds behind the attempted invasion of Earth in the series Threshold.


The aliens homeworld is briefly seen in the dreams of those who have been exposed to the conversion virus. It is a surreal world covered in forests of glass trees with a stormy skies.


The motives behind the invasion where never revealed in the series. On infectee claimed that the aliens were actually saving mankind by sending the conversion virus to strengthen the planet and its population in preparation for a large radiation strike from two exploding stars. Despite this the aliens brutal methods and lack of empathy casts this theory in doubt. At the end of the series it is implied invasion was their intent but humanity will eventually drive them off.

The Signal[]

The crowning achievement of the aliens is a conversion program/ virus called the Signal. It is a combination of light and sound that is capable of altering the genetic structure of any living thing exposed to it into an alien infectee. The signal is so strong that second and third century copies are capable of causing infection.

Only small Children are immune to the signal.

The Exposed[]

While the aliens intentions are to convert humans into their own kind several variants have occurred in those exposed to the signal that include:

  • Infectee: Humans converted by the alien signal into "aliens". They appear outwardly human but internally they have been altered to include a third helix. An infectee is stronger, faster and smarter that a normal human and "programmed" by the signal to spread the infection through whatever means. Mentally they have the characteristics of sociopaths; possessing no empathy or genuine human emotion.
  • Mutants: Humans who reacted badly to the signal, or who immune system proved more resistant than most to infection. They are grotesquely and fatally deformed by the signal. They will either mutate and die straight after exposure or mutate and survive for a time. Unfortunately the process drives the victim murderously insane.
  • Hybrids: An incredibly rare phenomenon where a combination of exposure and genetic defects in the victim cause the conversion process to stop halfway through without killing the victim. Hybrids possess the same strength, speed and endurance as an infectee but retain their humanity and emotions. They also possess the ability to physically see those who have been exposed to the signal by a blue green aura that surrounds the exposed. Despite this they lack the ability to distinguish between a person with minimal exposure and a full blown infectee.
  • Dreamers: People with minimal, harmless exposure to the virus. They are now attuned to the alien intelligence allowing them to listen on the invaders in vivid realistic dreams.