Mad, bad ‘Byron’ is fun, but is he full of hot air?

“Byron,” which airs Saturday night on BBC America, tells the story, in generally accurate terms, of the British Romantic poet George Gordon, Lord Byron, who before an early death from fever on an uncharacteristic freedom-fighting expedition to Greece, caused a stir in British society with both his art and his antics. It is well acted and fairly watchable, beautifully dressed, and covers a lot of ground without seeming too temporally splintered. But it is never particularly convincing and doesn’t add up to much in the end.

“Mad, bad, and dangerous to know,” is how Lady Caroline Lamb described the author of “Childe Harold’s Pilgrimage,” the narrative travel poem that made Byron, played here by Jonny Lee Miller (“Trainspotting”), a star at age 24. “I awoke one morning and found myself famous,” the poet wrote, and says here, and the scenes that portray his early and sudden celebrity are the film’s best. He curls his hair and puts on his poet persona to go out, rolling his eyes distractedly as women crowd around him, claiming to “eat only potatoes mashed in a little vinegar” but tucking into meat as soon he gets back home. (One thinks of David Bowie in his I’m-a-spaceman phase.) He is alternately obsessed with and amused by his own capacity for badness and transgression. It’s obvious stuff, the poet as pop star -- the sort of thing that used to excite Ken Russell, who had his own go at Byron in “Gothic” -- but fun nonetheless.

If Miller’s Byron is not quite one-dimensional, he is not quite three-dimensional either, but perhaps that’s just how it is when you’re playing a personality retrospectively diagnosed as bipolar. It’s one extreme or the other, though it just takes a glance at Byron’s own actual correspondence to get a sense of the recognizably normal person who lived in between. Much of his dialogue is awkwardly, even comically aphoristic, like stray lines out of “The Importance of Being Earnest”: “For a man to become a poet he must be in love ... or miserable.” “I like a woman to talk or I am left with the suspicion that she is thinking.”

It’s difficult to portray genius, or even significant talent, and “Byron,” directed by Julian Farino (“Our Mutual Friend” and lately a regular director of “Entourage”) and written by Nick Dear (“Persuasion”), doesn’t really attempt it, except in a roundabout way. “No one has ever written a poem like that before,” fellow scribe Shelley (Oliver Dimsdale) declares upon giving the manuscript of “Don Juan” a once-over, but that is not a sufficient recommendation. The occasional voice-over reading of a stanza, chosen to comment on the action or the poet’s state of mind, does a little more to communicate why someone bothered to make a movie about him, but still not quite enough.

One is never convinced he’s worth the trouble, and sympathies fly instead to the people who had to live with him. It’s these reactive performances that make the picture, in spite of its faults, worth a look. Especially good are Natasha Little as his half-sister and presumed lover, Augusta Leigh (the film presumes she is, though the matter is open to scholarly debate); Julie Cox as his not-for-long-suffering wife, Annabella Milbanke; and Camilla Power as the eccentric Caroline Lamb, who liked to dress as a page and seduces Byron in a taxi.

The reliable Vanessa Redgrave is here, not working particularly hard, as the poet’s confidante Lady Melbourne. Quiet comic relief is provided by Penny Downie and David Ryall as Byron’s in-laws and Philip Glenister, droll as his valet, Fletcher. It’s Fletcher, the patient ordinary man, who gets the film’s one happy ending, and to the viewer as well as the character, it feels like a kind of reward for having stuck it out.

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‘Byron’

Where: BBC America

When: 6 p.m. Saturday

Ratings: TV-MA (may be unsuitable for children under the age of 17)

Writer: Nick Dear. Dirctor: Julian Farino. Executive producers: Hilary Salmon, Laura Mackie, Andrea Miller, David Bernath.