a tv series can have a “theme” but more importantly, it needs what i call the “operational theme”: the thematic desire of the protagonist that fuels season after season.
in a procedural this is cut and dry - the protagonists are dedicated to - literally “law & order”.
in more modern television, the “operational theme” of “breaking bad” - for example - begins as walt’s need to save his family at all means but is later revealed as his own attempt to self actualize and stave off death by doing the one thing at which he truly excels but no one appreciates.
your series can have a lofty, intellectualized theme - the kind of thing that fuels criticism and college-level papers - “power,” “alienation,” “the shallowness of modern life” or “the banality of evil”…
…but without an operational theme - one that can support a number of variations of action while supporting a consistent emotional need - you don’t have a series and you are not succeeding as a televisual dramatist.
my favorite example of the perfect fusion of plot, story and operational theme is the film “die hard”. the entire movie is a metaphor for marital therapy, the operational theme is a husband trying to earn back his (for good reason, by the way) estranged wife.
the terrorists in “die hard” are really a metaphor for what keeps john mcclaine estranged from holly: as with any person in marriage counseling, john mcclaine loses his metaphorical armor as he fights the barriers to the point of emotional exhaustion… he ends up blubbering to his “therapist,” having lost his weapons, shoes and clothes.
he’s bleeding both thematically and practically.
the bathroom confession in “die hard” could have just easily been an episode of “in treatment”: a man denuded through adversity of all the trappings of pride.
what makes “the shield,” “the sopranos” and “breaking bad” interesting is that the operational theme is the tragic struggle of their protagonists to NOT change.
walter white, tony soprano and vic mackey - and don draper, as well, as he pursues a life that is essentially a fantasy construct of his grotesque childhood - want their cake and eat it too.
this desire, to remain evil - and delusional about that evil - in spite of its corrosive influence is where every last bit of the drama of those series lies. that is why they last - until the protagonists are either stripped down to their most base emotional reality - their core level trauma - or destroyed.
let’s say you are creating a series. unless you truly know what your protagnist’s operational theme is - the basic want that propels episode after episode, all the thematic intellectualizing in the world won’t help you or your series survive.
many ideas have tap danced around a lack of an operational theme for a while - a pilot, maybe even a season of decompressed cable-style narrative. but at the end of the day, a stark, robust, and recognizable operational theme is the sun source of all televisual drama.