The Assassin review: Keeley Hawes and Freddie Highmore thriller is at its best in smaller moments

Both series also star Shalom Brune-Franklin in a pivotal role, and both operate in a similar tonal space - not quite comedy, but certainly not deadly serious either. Everything's just that little bit out of whack with the real world, but whenever you're laughing too hard, the show will quickly bring you back down to earth.

There's also plenty of action in both series and secrets galore. No matter how different the tone may be, these are still shows operating with classic thriller conventions.

Thankfully, The Tourist was great, so The Assassin being in any way similar to it can only be a good thing. It also has one key element which is totally unique - and that is where the series shines brightest.

The Assassin follows Hawes's character Julie, a retired assassin living on a Greek island, who seems to still have some yearning for her former life. Meanwhile, Highmore plays her estranged son Edward, who is visiting her to try and reconnect when it all kicks off.

Julie's past catches up with her in a big way, and the duo find themselves on the run, on a journey which takes them away from the island and deep into the heart of a conspiracy.

The Assassin is one of those shows that it's quite difficult to talk about. The twists and turns come thick and fast, and one wouldn't want to spoil any of them ahead of time, not least because they really are quite good and legitimately surprising.

However, what I can say is that the best part of this show is, no doubt, the relationship between Julie and Edward.

You could imagine a version of this where Julie is outwardly the perfect, caring mother, whose dark secret is well-buried. This series does something much more interesting, in that she is incredibly abrupt and distant. She and Edward, who is quiet, polite and warm, could not be more different.

The mother-son verbal sparring matches that continue across all of the episodes are excellently scripted, hugely entertaining and funny, and a joy to watch.

As the Williams brothers themselves have noted, this is a dynamic we're far used to seeing with fathers and sons rather than mothers, so to see Hawes on biting form here helps to detract from any feelings of over-familiarity with the more traditional genre elements of the series.

It's also perhaps for the best that Edward's 'wounded pup' routine is never 100 per cent easy to sympathise with. Highmore gives the character a slight edge beyond simply being the 'good cop' to Julie's 'bad', which makes us feel just a little more wary of him, but also more excited to be in his presence.

It's the smaller moments between the pair, where they're just chatting, arguing or even bonding, that see this series at its peak and at its most innovative.

The rest of the cast are great here too, even if some of their characters are a little more closely aligned with the stock and trade of this genre.

For instance, there's Alan Dale's cold and ruthless businessman and Gina Gershon's mysterious grenade-like character, thrown in to cause chaos given that we're never quite sure of her motivations or whose side she's on.

Meanwhile, Shalom Brune-Franklin and Devon Terrell play the children of Dale's character, both of whom have gone in different directions. She inherited his smarts and cunning, but appears to have more of a heart. He's a reckless idiot, with an insatiable drug habit and longing to finally gain his father's approval.

These are all important pieces of the puzzle that the Williams's have devised, as are mystery roles played by Jack Davenport and Richard Dormer. Everyone is clearly having a lot of fun here, enjoying blurring the lines between the comedic and perilous moments.

The Assassin also benefits from the fact that it's a glorious visual spectacle. Of course, this is in parts thanks to the stunning locations, as the series traverses a number of different countries and locales.

It traces Julie and Edward's journey from remote outposts to glamorous, high-life settings from bustling cityscapes to breathtaking rural environs.

But it's also thanks to the work of production designer Scott Bird and of directors Lisa Mulcahy and Daniel Nettheim. For one thing, they have helmed some glorious action set-pieces here, which are riveting and the perfect blend of both structured and visible, yet chaotic and frenetic.

As for how the plot shakes out, and whether the resolution is satisfying, it's hard to say. Only four of the six episodes have been made available for press in advance of the show debuting, meaning that I myself am still awaiting the answers to some of its most pressing mysteries.

One thing that is known is that there will be a firm resolution. The Williams brothers have said that, while there could be more of The Assassin in future seasons, there doesn't need to be. Like most of their series, all the pressing storylines is wrapped up within one season.

This certainly gives hope that the series will stick the landing. For now, all I can say is I had a blast with the first four episodes.

They may not be revolutionary, and may give you some déjà vu to past Williams joints, but if you're looking for entertaining action, some fun twists and a compelling central character/relationship study, then you will certainly find all of that here.

The Assassin premieres on Prime Video on Friday 25th July – you can sign up now for a free 30-day Prime Video trial.

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