Granted, 'F.Z.Z.T.' takes a little while to get going - the episode's first half falls squarely into procedural territory as the team track a series of electrostatic anomalies and deal with a deadly trinket left behind by Avengers villains, the Chitauri.
The nature of the threat isn't startlingly original either; the effects of the Chitauri virus - transforming innocents into human bombs - is almost identical to the fallout from Extremis, which we've seen in two previous SHIELD episodes.
But once our heroes return to the air and Simmons (Elizabeth Henstridge) is diagnosed with the virus and quarantined, 'F.Z.Z.T.' too begins to soar...
Henstridge and her on-screen partner Iain de Caestecker are both charming performers, but have perhaps been hamstrung in previous weeks by their limiting 'geeky odd couple' roles.
Here, both have the chance to dig a little deeper and it's their powerful turns that keep the viewer hooked throughout the remainder of the episode.
Credit also to writer Paul Zbyszewski whose script twists and turns, packing in a powerful 'happy ending' fake-out and a final cruel shock as Simmons jumps from the SHIELD craft, unaware that Fitz's 'anti-serum' really does work.
Only the ultimate climax - in which Ward (Brett Dalton) leaps from the plane to save Simmons - rings false. After a string of tense and intimate scenes, Ward's action man antics feel out of place - silly and overblown.
'F.Z.Z.T.' is not perfect, then - with a slow opening and a misjudged payoff - but what it is is a strong retort to those who've accused Marvel's Agents of SHIELD of being glossy but empty, slick but soulless.
Here's an episode with plenty of heart and a pair of fantastic performances at its centre.
Make Mine Marvel! - The entire episode is essentially a semi-sequel to The Avengers and Titus Welliver even reprises his role as SHIELD's Agent Blake from Marvel One-Shot, 'Item 47', which also dealt with a discarded piece of Chitauri tech...
Plus, Captain America gets a nod from Skye (Chloe Bennet), while Coulson (Clark Gregg) makes a (dreadful) quip about Iron Man.
Coulson Lives! - So 'F.Z.Z.T' contained some pretty major developments on this front…
So Coulson is fully aware that there's more to his 'death' and miraculous resurrection than he's been told and that he's "different" now - even subjecting himself to a full physical.
The tests show he's perfectly fine and perfectly human - he even still bears the scar from Loki's weapon. But Coulson - and Melinda May (Ming-Na Wen) - both know that something's not right...