"Percy Jackson and the Olympians" doesn't have a history of lightning strikes on the screen.

Two critically panned film adaptations of Rick Riordan's best-selling kids' books series − "The Lightning Thief" (2010) and "Sea of Monsters" (2013) − greatly disappointed fans (and the author) and sputtered out at the box office. A decade later Disney+ is trying to right the creative and commercial wrongs of the movies with a new TV series created by Riordan himself, along with producers Jon Steinberg and Dan Shotz.

"Percy Jackson and the Olympians" (streaming Wednesdays on Disney+, premiere episode is also on Hulu; ★★ out of four) certainly lacks the glitzy Hollywood makeover the movies gave Percy and his two main companions, casting age-appropriate actors. It also keeps the scope of the story distinctly down to Earth (well, when it's not on Mount Olympus). The resulting series has already received a great deal of advanced praise from book fans, but every TV show based on a book, comic or video game has to stand on its own. "Percy" doesn't have quite enough substance and panache. Confusing, with jagged pacing and an over-reliance on novice young actors, "Percy" just doesn't quite click. It strides for epic but ends up far more ho hum. It might delight devotees and young kids with a twinkle in their eye, but unlike the best children's media, it's unlikely to draw in the parents stuck watching it too.

Percy Jackson (Walker Scobell) is a 12-year-old outcast living in New York with few friends and a lot of strange occurrences in his daily life. One day Percy discovers that he's no normal tween but in fact a half-blood demigod. All that Greek mythology he learned about in English class? It's all real, and now monsters like minotaurs and furies are after him.

Percy's adventure takes him to Camp Half-Blood, a summer camp full of surly, superpowered, part-godly adolescents. He's barely settled into his new life when he is given a mandatory quest to stop all-powerful gods like Zeus, Poseidon and Hades from going to war (and might just help him rescue his mother). With his friends (or frenemies) Annabeth (Leah Jeffries), daughter of Athena, and Grover (Aryan Simhadri) a mythical satyr, Percy sets out for the wilds of, well, rural New Jersey and the other unseen magical parts of the regular world.

If it sounds like a lot to take in, it is. And unfortunately the series does a poor job explaining it all. The pace, particularly of the first three episodes, is all wrong, with the momentum of fight scenes, prepubescent outbursts and exposition sessions by emotionally distant adult authority figures starting and stopping jarringly. It's as though Riordan and the other writers were unsure where and how to split the story up into the series' half hour episodes, so chose beats at random. The story hardly seems to have begun, and then suddenly you're halfway through.

Without a firmer background given to the audience, "Percy" struggles to create effective stakes. It also doesn't help that at times the young actors, while talented, lack the full range of abilities and nuance to create emotional depth in some of their scenes (they are not alone, just go back and watch the early "Harry Potter" movies). A bevy of famous adult guest stars does little to help this other than distract. Lin Manuel Miranda as Hermes? Megan Mullally as a fury? I guess it works, but neither brings much to the series other than their famous faces.

But it is not all bad news. By the fourth episode, "Percy" and its young stars have found more of a rhythm. The plot still might not make much sense to many viewers, but at least everything feels a little more dangerous, more emotional and more magical. After all, what's the point of finding out you're secretly part Greek god if there isn't a little magic behind all the mayhem?

According to Riordan and the producers, fidelity to the original story was the highest priority in the Disney+ series. As a nonreader I can't judge them on that. But I can say, that worthy goal sometimes gets in the way of a more important one: creating a good TV show. If only the gods sent Percy on that quest.