
...between the UNKNOWN...
Westworld Season 2, Episode 6

It is also UNKNOWN
Money Heist Season 1, Episode 12

"A yet UNKNOWN number
of robbers gained access...
Money Heist Season 1, Episode 6

takes a bullet to the face
from a person or persons UNKNOWN.
Breaking Bad Season 4, Episode 7

with an UNKNOWN virus!
Money Heist Season 3, Episode 4