It's a sign of Nolan's appeal that an Oscar-winning best actor showed up to film two scenes for this. The cast is a veritable who's who of A-list power players and regular character actors from top tier TV shows. There's a dizzying array of them and at some point you may find yourself just surrendering to the fact you can't hold them all in your head and you just have to enjoy the drama. And what drama it is. Nolan has drawn from Cillian Murphy a true performance for the ages. He plays it with subtlety and nuance, rarely lapsing into clichéd mannerisms or line delivery. That's not to say the script lacks such tropes; Matt Damon, there to provide propulsion and pace (and boy does he achieve it) ticks off a few OTT lines in amongst his otherwise excellent performance. Downey Jr. is a surprisingly restrained presence in the first half of the movie but does lapse into his comfort zone in later scenes. But the acting is only half the story. As with all Nolan films, the sound, cinematography and editing are characters in themselves. This may take Tenet's crown as THE LOUDEST FILM EVER MADE. To watch it in IMAX is to have your seat constantly rattling and shaking. The plot is constructed in a Citizen Kane style, cross cutting from decade to decade, charting Oppie's meteoric rise and fall from grace. And it looks beautiful. The elegant black and white is mixed with colour effortlessly; the sets move between glossy and glamorous restaurants, prestigious University lecture halls and quickly constructed wooden towns to claustrophobic interviews rooms. Every setting feels absolutely real, thanks largely due to Nolan's eschewing of CGI. And finally, there's the science. Just as Nolan made cinematic candy of black holes and time dilation in Interstellar, so here does he serve up slices of quantum mechanics. He doesn't pause to explain a lot and only offers the occasional visual reference. But if you don't know the difference between fusion and fission, A-bombs and H-bombs or uranium or plutonium, fear not: the characters' reactions let us know whether the development is good or bad. Pacing wise, it's a game of two halves. The race against the Nazis is blistering and ends with one of the most unbearably tense scenes you'll see on screen this year. The cold-war conspiracy scenes feel longer and slower, deliberately so. Nolan's use of sound and horror imagery to convey Oppenheimer's guilt after his impossible Catch-22 is nothing short of genius. This is not Nolan's best film but in its depiction of humans dealing in incomprehensible powers than can do irreparable harm to our planet, it may well be his most important.