That model has gradually been eroded in favour of the story arc format. In this format TV episodes have to be viewed sequentially and feature building storylines, continuous character developments and, in extreme cases, the idea that no episode can end with characters in the same places they started in. Storylines could build from unlikely sources, with a single line of dialogue from twelve episodes earlier suddenly proving pivotal to the resolution of a long-running plot, or a minor character established in an earlier episode suddenly becoming a major player.
"Right, so whilst this is chronologically our fourth appearance from the viewer's point of view, it's actually our fifth from within our internal timeline."
"Have you factored in the new post-2005 series?"
"Ah crap, wait whilst I figure that out..."
"Have you factored in the new post-2005 series?"
"Ah crap, wait whilst I figure that out..."
Story arcs are, of course, not new. Both radio and television soap operas stretching back to the 1950s or even earlier have been built on the same model, whilst in the 1930s serial movies like Tarzan, Flash Gordon and Buck Rogers (all starring Buster Crabbe) pursued the same idea. Doctor Who, which began in 1963, was made up of serialised storylines, with each storyline typically running between three and six half-hour episodes in length (with outliers as short as one episode or as long as twenty-six), and minor storylines running between serials, particularly in the earlier seasons when each serial had an ending leading into the next and recurring enemies like the Daleks and Cybermen (and, to a lesser extent in Patrick Troughton's tenure, the Ice Warriors and Yetis) appearing with some regularity.
In American television an influential show for the development of the story arc was The Fugitive ("A Quinn Martin production!"). This was mostly an episodic story in which Dr. Richard Kimble is on the run from the police for a crime he did not commit, and as he fled the law he helped other people who were in trouble. It wasn't until the fourteenth episode of the first season that we learned what the crime was that he'd been accused of and what his ultimate goal was, of finding the 'one-armed man' who killed his wife and clearing his name. Also unusually, the series didn't just keep this as a remote goal on the horizon, but several times brought Kimble and his nemesis into contact with one another. Also, and this truly was and remains highly unusual, The Fugitive got a proper ending, in which after four years the one-armed man is apprehended and Kimble's name is finally cleared. The Fugitive's final episode in 1967 was watched by three-quarters of the American viewing public at the time, a colossal amount and arguably the result of people wanting to see how this story that had been unfolding for four years was wrapped up.
Still, the traditional arguments in favour of episodic television remained strong, and arguably even The Fugitive was still mostly episodic, with the 'anchor' arc episodes only occurring at rare and key moments in the series, with all the in-between installments still watchable in isolation on their own merits. In fact, even the utterly bonkers British genre series The Prisoner arguably only needed the first and last two episodes to stay where they were, with the rest of the episodes interchangeable in order.
The reason why episodic television was favoured in the States was due to the power of syndication, where TV shows were sold into constant re-runs after their original airings on the networks, and selling a show into syndication was often essential to turn a profit. The local channels carrying the shows on syndication were not particularly bothered about showing series in the right order, so making each episode stand alone as possible was a key concern for TV producers. Ironically, soap operas were able to overcome this influence by their very disposability (each individual episode costing peanuts compared to a weekly drama) and their sheer mass of episodes.
This 'syndication trap' was responsible for putting down even successful shows. The original 1978-79 Battlestar Galactica had a definitive opening story arc (the destruction of the Twelve Colonies and the flight of the survivors into space) followed by a series of stand-alone episodes, but these were punctuated by occasional shifts in format. For example, Baltar is captured by the Fleet in one episode and remains a prisoner for several weeks before staging a break-out, whilst one regular character established in the pilot dies three weeks in. Halfway through the season the battlestar Pegasus arrives and, although it doesn't stick around, several crewmembers (including a new regular) join the Galactica crew. The second half of the season also sees a building storyline in which mysterious alien spacecraft apparently made of crystal starts shadowing the Fleet, and at the end of Season 1 a hint to the location of Earth is discovered. BSG's cancellation at a time when it was still getting 15-20 million viewers a week remains baffling to this day, despite its enormous-for-the-time budget, but certainly the show's serialised storyline not being popular with syndication channels has been occasionally put forward as one reason why it was dropped.
Over in the UK, with no comparable phenomenon to syndication, this was less of an issue. Shows were typically shown once, maybe repeated a year or so later, and then disappeared for good, often literally as the BBC would wipe the video tapes for re-use (although thankfully they had abandoned this practice by the late 1970s). In particular, during the 1970s the BBC got into the swing of making 'event' mini-series based on books, such as their ambitious adaptation of War and Peace starring Anthony Hopkins or I, Claudius starring Derek Jacobi and John Hurt, and these serials would obviously include epic and detailed storylines spanning many episodes to some success.
In SF&F terms, Doctor Who was continuing and had flirted with a much longer form of storytelling in its sixteenth season in 1978-79, which consisted of one big meta-narrative called The Key to Time, divided into six sub-serials. This huge narrative, partly written by Douglas Adams, proved successful and for several seasons the show continued to pursue larger narratives, such as a 'trilogy' of serials two years later where the TARDIS was trapped in another dimension called E-Space (with the purpose and fate of E-Space then revealed in the season-ending, Doctor-replacing episode Logopolis).
However, an arguably more influential (and I'll explain why in a moment) SF TV series also debuted in 1978. Written by Terry Nation, the creator of the Daleks, Blake's 7 was, at least conceptually, a rip-roaring space opera, complete with a heroic crew of seven do-gooders fighting the evil forces of the Terran Federation. In real terms, the show undercut its own premise almost from day one. The show was, to start with, very heavily serialised. The crew come together slowly, with the full roster only being completed after the first four episodes. Their mode of transport, the alien starship Liberator, was only discovered in the second episode and turned out to be a threatening force in its own right, routinely threatening the crew with death through its defence mechanisms or the callous disregard of the ship's sentient AI for most of the first season. Blake would routinely mention a Federation military target he wanted to destroy and this would then show up as the next planet they visited a week or two later. Half the crew wanted to kill the other half. Often individual Federation personnel were revealed to be perfectly decent, good people just doing a job to feed their families and unaware that their role as cogs in the machine was causing greater suffering elsewhere.
Blake's 7 was brilliant, bleak and subversive, having more in common with Nineteen Eighty-Four and even The Prisoner than with matinee serial Westerns or other heroic stories. One of the reasons for its brilliance was definitely its story arc. Regular characters died, often with zero forewarning, and new ones joined. There was a recurring cast on the Federation side devoted to catching our heroes. Blake and Avon's relationship developed from mutual distrust to grudging respect only because Blake agreed to give the Liberator to Avon once his dream of a general uprising against the Federation had been achieved (a promise Avon calls on Blake to deliver in the Season 2 finale). Most of Season 2 was dedicated to one storyline as the crew desperately hunted for the Federation's central command and control centre, hoping to destroy it and plunge the Federation into anarchy from which a revolution could be launched. Then, at the last moment, a completely new threat dwarfing that of the Federation arrived. When the series finally ended in 1982, having lost Blake, the Liberator, most of the original cast and all but one of the recurring villains along the way, it ended on a jaw-dropping, mind-blowingly nihilistic and even cruel note that left the viewers completely bewildered and the show's place in the canon of TV science fiction forever secure, even if the show's profile would eventually decrease over time.
Ironically, of course, Blake's 7's 'revolutionary' approach to genre television was achieved mostly by accident. Nation planned out the slow introduction of the cast simply because it was too expensive and confusing from a production standpoint to introduce them all at once. The Season 2 story arc was planned out in great detail and depth and then promptly had to be thrown out when the writers couldn't get the scripts ready in time, replacing it with a less complex storyline. The show was supposed to end with the much neater and, at least relatively, happier ending of Season 3 and only came back because the head of BBC drama liked the final episode so much he rang up the continuity announcer whilst the show was still on the air and told him to announce the show was coming back the next year. The supposedly apocalyptic ending of Season 4 was actually just a 'normal' cliffhanger which the writers could overcome easily for the next season, in which they hoped to resolve the story more traditionally, but the show was cancelled instead, leaving that ending as the series' last word, which hadn't been planned.
Given that its storyline had unfolded as a happy accident, why was Blake's 7 so important and so influential on the gradual shift to arc series that followed, given than most people don't even know the name today? Simple. Two young Americans were watching the show at the time and taking mental notes. One was called J. Michael Straczynski and the other was called Joss Whedon. We'll catch up with them next time.