Marvel's anchor ABC drama Agents of S.H.I.E.L.D. ended its second season with a overstuffed two-part episode all rolling out on one night. Appropriately, a lot happened over the two hours: the final conflict between S.H.I.E.L.D. and the Inhumans. The fate of Grant Ward and his faulty femme fatale Agent 33. Reconciliations for Skye's family and Bobbi and Hunter. Two dozen kick flips. CG effects both impressive and mundane. The arrival of a Marvel Comics supervillain. Deaths and maimings. And a kitchen sink's worth of clichés.

But more than anything, the season finale represented two things: a collision of the plotlines that represent the show at its best and worst (some in motion since Season 1 began) and a pitch to viewers for why Agents of S.H.I.E.L.D. deserves another year on the air. They seemed to convince the network that the proposition is worth it. Fandom may be a harder sell, but ultimately will be won over.

The pivotal action that spins the whole story forward is a classic face-heel turn from Skye's Inhuman-leading mother Jiaying. Though she's been played across the back half of this season as a benevolent force to counter deranged daddy Cal, her murder of S.H.I.E.L.D. heavy Robert Gonzalez was really just the tipping point that revealed Jiaying as an unbalanced Big Bad. Dedicated to hiding the Inhumans at all costs, she believes her goal can only be achieved when S.H.I.E.L.D. and all its agents are dead. Combine that with she and teleporter Gordon's quest to retrieve a Kree artifact from a S.H.I.E.L.D. carrier (a giant stone that at one point turns to liquid for no seeming reason at all), and you've got a plot with more than a few contrivances but enough momentum to push the finale past its awkward opening and into a more assured back half.

Part of the confusion is Skye's general sense of being adrift. During the extremely confusing opening where S.H.I.E.L.D. refuses to retaliate when one of their own is murdered and a Quinjet is stolen as a smoke screen, she casts her allegiance with the Inhumans only to immediately doubt the choice. Even though seasons-long foil Raina claims that Skye will have her head turned around loyalty-wise (part of a path to being an Inhuman leader...a plotline that should sooner be dropped than explored), our torn Agent is unable to accept the truth around her until she just so happens to walk in on her mother murdering Raina in cold blood.

Director Coulson is similarly ineffectual at the start. Faced with the biggest threat to S.H.I.E.L.D. since Hydra attacked, his "wait and see" approach may as well have come with dialogue explaining "I can't make a move until more of the plot is in place." As much fun as it is to watch Cal go through cartoonish hot flashes and cold sweats, the action of the show spins its wheels until the Inhumans can finally make their move.

More exciting and relatable is the rescue mission to save Bobbi Morse from Grant Ward and 33. Though the kidnapping plot itself made little sense and the way Hunter and Fitz crack it open is equally flat, Ward's slow boil torture of the woman known as Mockingbird is as tense and squeamish as anything the show has ever done. Though Bobbi's failed attempts to show 33 how her lover is trying to manipulate her fail, the Agents resolve ultimately save her from a quick end. If Ward and 33 can't find satisfaction in breaking her themselves, they'll do it by killing someone she loves. Sure, it's been done a million times before on shows like this, but execution is 90% of success in those cases, and the show executes flawlessly.

As the second hour opens up, Hunter and May's arrival to rescue Bobbi looks and feels more like a Jason Bourne movie than it does an ABC sci-fi drama in the best way. The sickly lighting and handheld camera work heighten the tension as they work their way through the compound thinking they may have lost Bobbi already. When finally confronted with the booby-trapped death door Ward left for Hunter, the show zigs in a few key ways to let Bobbi heroically take the bullet at the same moment Ward accidentally murders a May-faced 33. The parallel scenes of the men collapsing over the women they love are viscerally shot, well performed by all the actors and ultimately highlight what the turncoat S.H.I.E.L.D. Agent keeps in common with his former friends even as he's gone over the edge. Dynamite stuff.

Luckily, that sense of urgency and drama bleeds into the Inhuman plotline in hour two. Back at home base, Coulson, Fitz and Simmons are finally confronted with a Cal transformed into the beastly alter ego comic fans know as Mr. Hyde. While the cro-magnon makeup job done on Cal is hardly up to the standard of most Marvel Studios projects, it's almost a perfect capper to Kyle MacLachlan wildly ridiculous performance across the season. Few actors could pull off something so silly, but he does it with style to the very end. When Coulson traps Cal and forces him to confront the fact that his wife Jiaying has been the real villain all along, the more gentle moments the character has shown in recent weeks make his eleventh hour heroic conversion work in a way it shouldn't.

On the carrier, the Inhumans pretty much route all that's left of S.H.I.E.L.D. while also setting off the completely contrived "S.O.S." beacon that the episode draws its name from. The superpowered killing of a dozen red shirts and a handful of nuS.H.I.E.L.D. operatives that no one cares about could be completely lacking in drama if it wasn't for the timely intervention of Mack. As an previously unseen, still unnamed multiplying Inhuman douses the show in lame effects more fitting of a '90s era syndication series (like Mutant X...does anybody remember Mutant X?), actor Henry Simmons' "I'm getting too old for this shit" style and adherence to axe usage bolster the whole sequence even as his fellow agents arrive to join the fight. And his one-liners – from references to his Fox News-watching mother to "I'm the guy that kills Gordon" – all make perfect 10 landings in the otherwise jumbled landscape of fake spy jargon. Why didn't they try to get this guy a spinoff?

The final moments of the action sequence contain more than a few decent twists. Skye's confrontation with her life-sucking mom and subsequent rescue at the hands of Cal is a fine emotional capper to a storyline that was inconsistent across the season. Fitz's "I almost died but really I killed Gordon" moment after finally connecting with Simmons romantically is a worthy swerve akin to Hawkeye's final scenes in Age of Ultron. And Mack chopping off Coulson's hand as soon as he was infected with the Inhuman weapon is a legitimate "Holy shit" moment in a show that needs more of them. Even Skye's late game fight against Whatshername McRedhead had some panache as it led to a late game conversion of Lincoln. When Agents of S.H.I.E.L.D. revs up its action with real stakes, it can be a superbly entertaining little series.

The multiple codas at the episode's tail end are a microcosm of everything good and bad about the series. While the premise of a one-handed Coulson and Skye forming a "Secret Avengers" of powered agents is a great pitch for next season, it comes at the expense of almost no resolution of the Inhuman story's finer points (so is Lincoln the leader now or what?). Skye's brief moment with her mind-wiped dad was as satisfying as May's "Maybe I'm ready to be romantic again" exit was bewildering. And while Ward's claim to being new head of Hydra and Simmons last-minute absorption into the Kree artifact are both tantalizing cliffhangers, the "Inhuman crystals are now fish oil" finish is almost stunningly dumb.

For every step forward this show takes, there's an equal move back. That keeps things mildly entertaining but never transcendent. And all in all, that's not a bad fate for this pocket of the Marvel Cinematic Universe. See you next year.