Aired Tuesday, Apr 14 2015 at 8:00pm EDT on ABC

One of Agents of SHIELD‘s winning qualities has always been its intense humanity. The show doesn’t simply want us to root for Coulson and company. It demands that we care about the characters too – see them as independent actors with hopes, fears and scruples rather than mere jump-suited pawns in a bigger story.

The point is brought forcefully home in ‘Melinda’, one of the season’s most moving episodes yet. A two-hander, it delves into Agent May’s brittle past, detailing her transition from contented suburbanite to high-kicking force of nature. Side-by-side, we witness Skye’s difficult journey as she reconnects with mother Jiaying and, along with the viewer, learns to see wacky, despicable father Cal in a new light.

© ABC / Patrick Wymore

May (Ming-Na Wen), Coulson (Clark Gregg) and Hart (Terrell Tilford)

In less adroit hands, such melodrama might have added up to a soufflé of sentimentality. SHIELD, though, has never engaged in soap opera for the sake of it and it is obvious throughout that the flashback to May’s ‘origin story’ – which is really what it feels like – is relevant to her ongoing struggle to make sense of Coulson’s secret plans for SHIELD.

The cold opening presents us with a happily married May of seven years ago flirting with husband Andrew Garner. It is a shocking initiation: May is so bubbly – so… normal. Clearly infatuated, the couple talk about starting a family – when Coulson crashes their breakfast, May’s response makes it clear she sees herself as loving wife (and aspiring mother) first, SHIELD operative second. What could have happened to so utterly change her world view?

The answer lies in Bahrain, where a super-powered Afterlife escapee named Belyakov has gone rogue. Approaching her at an open-air cafe in a scene that might have come straight from black-ops romp Homeland, it is immediately clear that Coulson’s ‘softly softly’ approach is a bust.

© ABC / Patrick Wymore

Winter Ave Zoli as Belyakov in ‘Melinda’

Belyakov signals her unwillingness to negotiate with SHIELD by casually causing a table to fly across the courtyard, then seeks refuge inside an apartment complex, with an entire SHIELD platoon held hostage.

Local forces are predictably keen to level the whole neighbourhood. Coulson, however, has one last gambit – send May in to mop up. This, we are given to understand, is how she came by her sobriquet ‘Cavalry’. She has always hated the nickname, but why? Who wouldn’t want to be synonymous with a dashing last-minute rescue?

Back in the present, Skye is learning to master her powers, with the help of Jiaying. The initiate causes an avalanche (on purpose this time), then gets all reflective and melancholy. She’s worried she is starting to feel comfortable in Afterlife – and that’s bad news because, as an orphan, she understands that the instant she thinks of somewhere as home, it is snatched away from her.

As she relays the sad particulars of her childhood – a blur of foster families and rejection – Skye’s confession proves too much for Jiaying, who reveals SHE is the fledgling Inhuman’s mother, and that she was required to give her up for her daughter’s safety. Cue simultaneous mom-and-daughter blubbing – a nicely intimate moment the show is clever enough not to linger on.

© ABC / Kelsey McNeal

Luke Mitchell as Lincoln

Over at SHIELD, present-day May is conflicted. She was completely unaware Coulson was in contact with Deathlok and fazed when Bobbi and the rest of ‘new’ SHIELD reveal her boss and mentor was working on a globe-trotting secret project – in cahoots with her now ex-husband Garner at that.

Most damning of all, interjects Mack, the SHIELD nabob had been stocking up on bunk beds. Come on – who would spend their entire weekend at IKEA if they weren’t planning a covert silo of superheroes (who have to sleep somewhere like the rest of us)? Obvious, really.

May isn’t buying it – not completely. Sure, Coulson behaved shadily. Still, she retains enough loyalty in the commander to convince herself he must have had his reasons. All she needs is for Simmons to open Fury’s Toolbox and the truth will out. Um, stutters Simmons, who helped Fitz smuggle the REAL Toolbox off base last week (later, Fitz activates the box, and reaches out to Coulson and Hunter).

While Skye is having a wobbly-lipped reunion with the mother she never knew, Raina’s stay in Afterlife continues to prove unsatisfactory. Revolted by her spiny new appearance, she rejects Gordon’s assurances that things will get better (and a guy without eyes should know). More than that, she resents Skye’s freedom – her former compadre can go where she wishes and Raina remains a glorified prisoner, one haunted, at that, by dreams of Skye tucking into dinner with Jiaying and Cal.

© ABC / Kelsey McNeal

Ruth Negga as Raina in ‘Melinda’

We soon learn Raina’s nocturnal imaginings have the quality of a prophecy. At Jiaying’s behest, Skye indeed reconnects with Cal, also a prisoner at Afterlife. The three sit for a meal, with Kyle Maclachlan perfectly conveying Cal’s mixture of awkwardness and joy. It’s weird for him to reconnect with his estranged family – but wonderful too, and the slightly desperate glimmer in his eyes conveys the muddle of emotion.

There’s lots of touchy-feely gooeyness floating about – which makes the episode’s emotional payoff doubly devastating. As requested by Coulson, Flashback May infiltrates Belyakov’s bunker. She fights sundry goons, then takes care of Belyakov – shrugging off the rogue Inhuman’s crazy talk about wishing to feel the whole world’s pain. As relayed in voiceover by Jiaying, however, we learn the Russian wasn’t merely unhinged. She had a daughter, for whom she stole Terrigen Crystals, before fleeing Afterlife.

Alas, the little girl cannot control her abilities – as is horrifically clear when she steps from the shadows and confronts May over the death of her mother. Able to fatally leech a victim’s ‘pain’ with a simple touch, she looms over May, a trail of corpses in her wake. Something inside the agent dies as she squeezes the trigger and kills the little girl – shortly before Coulson rides to the rescue and it is falsely assumed that May took out an entire squad of bad guys (hence ‘Cavalry’). In Afterlife, Jiaying explains this is why her relationship to Skye must remain secret – post-Belyakov, mothers and daughters in cahoots are regarded with suspicion.

SHIELD has carried the day, yet May is broken inside. She recoils from her husband’s embrace and transfers to a desk job on the Avengers Initiative. She has killed a child – a highly dangerous one admittedly – and can never again think of herself as a wife or potential mother. It’s a bleak conclusion to a dispatch that came by its emotional impact honestly.

Agents of SHIELD will doubtless have more explosive moments through the current season – but it is difficult to imagine any matching this episode’s aura of quiet tragedy.