TV shows based on historical figures normally come in one of two settings.

They're either salacious and scandalous, holding up a side of a public figure that's never been seen before and done with enough gusto to make you second-guess what you think you know. The other setting is one where modern sensibilities are applied, and we're shown how forward-thinking that person was, and how they helped to move things closer to where we are now.

'Leonardo', a new series starring Aidan Turner and Freddie Highmore, plants itself somewhere between the two and never really lands on anything particularly inviting in the two episodes we've seen so far. The show opens with a much older, heavily bearded Leonardo da Vinci - played by Turner - who has been accused of murdering a young woman and is being interrogated by an ambitious Freddie Highmore, who looks ridiculous with a beard.

The story cuts back to Leonardo as a young man in the service of Verrocchio, played by Giancarlo Gianni, learning his trade as an artist and an engineer, and seeing the world differently from everyone else. Well, of course he would, but the larger problem with 'Leonardo' is that it fails to make Leonardo da Vinci in any way exciting or inspiring to watch. The reality is that Aidan Turner, playing Leonardo as a younger man, doesn't have any sense of himself and plays the role far too heavy, and without any kind of natural ease.

Yet, frustratingly, when it flashes back to him as an older, more bearded Leonardo, Turner's performance feels more convincing and intriguing than anything up to that point. It may be that he's had so much experience playing a smouldering type in 'Poldark' that it comes naturally to him, but the boyish exuberance that makes up so much of his performance just doesn't suit him.

It doesn't help either that the writing in the two episodes isn't particularly exciting or compelling. In fact, by the end of said two episodes, there was no real desire to see what happens next. Sure, there's a murder-mystery component in the story, but who cares? Leonardo da Vinci is such a well-known figure in history that the idea of him being involved in a murder would make up a big part of his cultural identity. Therefore, we have to conclude - again, without seeing the rest of the series - that he wasn't involved in said murder, meaning it has no further meaning in his story. Why put it in, then? Is it simply a storytelling device and nothing more? Surely a life as broad as Leonardo da Vinci's might have some more exciting stories to tell. What about his work with Cesare Borgia, or his battles with the Church?

Sure, you'd normally have to ramp up to those and lay the groundwork for them, but it's da Vinci. Most people have a working knowledge of his big hits, so why the need to labour over his early life when the exciting stuff is off in the distance?

For a show that's as bland as this, and with a subject matter that's so rich in material, you have to wonder how long it's going to last and if anyone's going to be interested enough in it to make the investment of time when there are far better shows on offer. National Geographic's 'Genius' series, for example, does this kind of thing with far more gusto and flash. 'Leonardo', sadly, spreads the paint too thin and doesn't have enough to make up a full picture.