Amnesia is all the rage on the big screen this week. Basic memory loss powers the adventures both of the eponymous spy in Jason Bourne and the blue tang fish in Finding Dory.
But the hero really swimming against the tide isn't the one with fins.
He is played, as in the first three Bourne films, by Matt Damon, who was absent from the last one, 2012's The Bourne Legacy. A good job, too; it was a decidedly muddled and overwrought affair.
But the return of Damon, and of director Paul Greengrass, nine years after they teamed up for The Bourne Ultimatum, brings back all the exhilarating if rather po-faced entertainment to a movie series that seemed to have run out of puff.
Jason Bourne, the film, has more puff than a nuclear cooling tower. It is basically one long, frantic chase, enlivened by Greengrass's trademark jerky camerawork and punctuated by occasional nods to the need for an actual plot.
Still, Greengrass, who with his editor Christopher Rouse also co-wrote the script, does his best to make the narrative relevant to 2016, chucking in references to the whistle-blower Edward Snowden, and to government-sponsored data hacking, enabled by a billionaire social media tycoon (Riz Ahmed) who may or may not be inspired by Facebook's Mark Zuckerberg.
It kicks off, though, in a sweaty Balkan clearing where Bourne — like James Bond a loner and maverick, but no more likely to issue some sparky innuendo than flaunt a spare tyre — seems to be earning his corn as a bare-knuckle prizefighter.
The implication that this is actually a more honourable living than international espionage is soon amplified when he is dragged back into the cross-hairs of his former employer, the CIA, by his old colleague Nicky Parsons (Julia Stiles).
Parsons has pinched some top-secret information about Bourne's own stalled operation, the notorious Treadstone programme, that — shock, horror! — reveals the agency to have somewhat less-than-noble intentions.
The stolen files also seem to shed light on the violent death of his CIA operative father. And of course Bourne, who can still barely remember his own name, needs all the help he can get in piecing together the jagged fragments of his past.
But he has never forgotten how to abseil from the roof of a tower block, or kill a man in 50 different ways.
This is just as well, because the dangerous security breach has alarmed the CIA's new director Robert Dewey (Tommy Lee Jones, on top form) and his lovely, improbably young protegee Heather Lee (Alicia Vikander, also excellent).
Incidentally, pairing Vikander and Jones looks like a casting director's joke; she has the face and complexion of an angel, while his might be a relief map of the Appalachian mountains.
They also differ markedly in their plans for Bourne. Lee wants him alive, hoping to bring him back into the fold.
But Dewey has a more sinister scheme and deploys his prize asset, a crack assassin (very nicely played by Vincent Cassel) to carry it out
It's thrilling stuff, and really does compound Greengrass's reputation as a terrific action director; a couple of the chase scenes make Bond's latest antics look almost pedestrian.
Moreover, as speculation continues to froth over who might be the next 007, with Idris Elba reportedly declaring himself too old at 43, it's worth noting that 45-year-old Damon still cuts quite a dash hurtling across rooftops.
It's good to see him back: a "Bourne-again" action hero!