The world is changing rapidly. The release of the terrigenesis crystals has converted dozens of people across the world into super-powered Inhumans, triggering panic. SHIELD are trying to keep a lid on the crisis, but officially they no longer exist and their authority and reach has been dramatically reduced. One of their number is also missing, whilst another has defected to Hydra.
Way back in 2013, Agents of SHIELD launched as the first TV spin-off from the Marvel Cinematic Universe. Its first season had a mixed response, mainly due to an early run of dull, procedural episodes only enlivened by a game main cast. However, a tie-in with the film Captain America: The Winter Soldier dramatically changed the show's fortunes as it became a much more compelling, pulp action show. The second season continued being solid, but was let down a little by an over-focus on the Inhumans arc, which had been drawn out over too many episodes.
Season 3 picks up where Season 2 left off, with SHIELD trying to contain the Inhuman problem by helping "good" Inhumans and neutralising "bad" Inhumans who are using their newfound abilities to commit crimes or hurt people. Making these kind of moral judgements whilst the governments of the world only want all Inhumans destroyed or neutralised becomes an increasingly difficult situation for Phil Caulson and his agents. The moral murkiness of this storyline is a nice contrast to the more straightforward good-vs-evil stories the show started off with and having to balance murky and shadowy agendas against one another becomes a satisfying source for tension across the third season.
The first half of the season focuses on the Inhuman issue and also on Hydra trying to satisfy the reason for its creation centuries ago, namely opening a portal to another world and locating the mysterious being known as "Hive." Jemma Simmons is MIA on that same planet (having been accidentally transported there at the end of Season 2). She is rescued relatively quickly, but it takes a while before she opens up about her experiences. This leads to flashback episode 4,722 Hours, oft-cited as the best single episode of the entire series for its balancing of horror and survival elements and for Elizabeth Henstridge's outrageously great performance.
Peaking so early does hurt the rest of the season a little (if not the entire series), which never really gets close to that level of quality again. However, the season continues to serve up some interesting stories and character arcs. Like the first two seasons, it helps that the season is split in half by a mid-season break, meaning it only has to sustain two 11-episode arcs rather than one huge 22-episode one. The shift in antagonist and story in the mid-season is handled well.
Handled less well is the abrupt departure of two of the series regulars. During the production of Season 3, ABC decided to commission a spin-off series following Bobbi Morse and Lance Hunter as the protagonists, so wrote them out of Agents of SHIELD in a manner that feels highly unconvincing. Then, of course, the spin-off was dropped after an unsuccessful pilot, removing the reason for them leaving in the first place. Although neither character is missed too much, the manner of their departure and their reasons for it feels contrived in the extreme.
The second half of the season is not quite as strong as the first, although it does stretch Brett Dalton's acting range. A veritable block of wood early in Season 1 (due to the writing choices), he improved immensely in Season 2 and in Season 3 he has to effectively play two completely different characters, and handles it well. However, the pacing in the latter half of Season 3 does feel a bit off and Hive using his mental powers to turn good characters "bad," only for the rest of the team to inevitably find a way of freeing them, is the kind of plotting that feels like it's on autopilot.
Still, Agents of SHIELD's third season (****) delivers effective, entertaining action and some nice character arcs. It also has the best episode of the entire series (4,722 Hours rates ***** by itself). It is available to watch, with the rest of the series, on Disney+ worldwide.