As the MCU turns 15, it’s time to start growing up. If not yet fully adult, Marvel’s latest series at least feels a bit more mature in design and ambition – a teenage franchise stepping out into the real world for the first time.

The inspirations here are clear from the off. Calling back the relative grittiness of the second two Captain America movies, and the films and shows that influenced them both (’70s political classics like Three Days Of The Condor and The Parallax View, modern spy shows like Homeland and The Americans), Secret Invasion opens like every good thriller – with someone running away down a shadowy side street.

This is Martin Freeman’s Everett Ross (last seen in Wakanda Forever), jumping off a rooftop in the first few minutes to end up in a puddle of blood on the pavement below. Except it isn’t really him. His face transforms back into a green alien elf – one of the shapeshifting Skrulls who are trying to bring us down from the inside with their magic powers of impersonation.

With a million Skrulls at large, and all walking around looking and sounding like humans (even the British Prime Minister, according to episode two), the threat here is one that can’t be punched or zapped or blown up like most of Marvel’s usual bad guys. Nuance, negotiation and espionage are the only superpowers at play here.

On one side we have Samuel L. Jackson’s Nick Fury (older, more jaded, now walking with a limp as he stalks through the series like an old-timey detective), Cobie Smulders’ Maria Hill, and Ben Mendelsohn’s defected Skrull double agent, Talos. The aliens have Kingsley Ben-Adir’s rebel leader Gravik and Emilia Clarke’s firebrand revolutionary G’iah. Then there’s Olivia Coleman’s grinning MI6 agent (cutting off fingers with secateurs and making wanking jokes) and Don Cheadle’s politico Avenger in a suit, James Rhodes. All double and triple crossing each other by the end of the first episode, there are no good guys and bad guys in Secret Invasion – just a lot of blurred lines and shady motives.

Setting the series in modern day Russia feels like the most pointed political jab Marvel have made to date – deliberately reigniting old Cold War sentiments at a time when real-world politics are starting to heat them back up again. It might be a stretch to directly compare Secret Invasion to the ’70s classics it clearly loves, but the ambition is there; and so is the gear shift. Burning slowly without any of the trademark banter that keeps the MCU light, the change of pace feels odd for a franchise built on flashiness, but it works. Clicking nicely after the first hour, the show’s real blockbuster strength is in its cast.

Arguably wasting the talents of half of Hollywood’s heaviest hitters for the last 32 films, Marvel here finally gives the likes of Jackson and Cheadle something to really bite into. Already looking to be to the MCU what Andor was to Star Wars, Secret Invasion is less of a sea change for Phase Five than it is a hint of growing maturity – a sign that Marvel can grow up with its audience if it chooses to.

‘Secret Invasion’ streams on Disney+ from June 21