Most modern media players (like VLC) allow you to right-click the video, go to the "Subtitles" track, and "Add Subtitle File" once you have downloaded the Greek .srt.

This is a three-part British crime drama starring David Morrissey as Vince McKee, an ordinary taxi driver who gets involved with a criminal gang.

Look for ".srt" files on reputable subtitle repositories like OpenSubtitles or Podnapisi by searching for the title + "Greek".

Tired of his life, Vince agrees to drive for a criminal acquaintance, leading him down a dark path that threatens his family.