Even as a heroin addict, Benedict Cumberbatch is riveting.

Through much of the pilot, the title character remains what he was bred to be: an English gentleman. He just happens to be an English gentleman with an extraordinarily nasty smack habit.

Cumberbatch is his usual convincing self as the druggy Patrick Melrose, meaning he’s often slimy, contorted in agony, and at points, looks as if he smells rather gamy. Yet when he’s onscreen in Showtime’s limited series, you can’t turn away for a second.

He commands every scene, an impressive job considering he spends a fair amount of time alone on screen. And while he handles dialogue with grace and style, some of his most impressive scenes are played wordlessly; in one, he uses that long body to druggily traverse a swanky hotel mezzanine as the floor rises up to greet him.

Translating Edward St. Aubyn’s richly literate prose certainly presented a challenge to the filmmakers: His five poetic books examine the interior life of a self-destructive yet self-aware man in a way that isn’t dialogue-driven or even obviously filmic. Yet Edward Berger’s direction and David Nicholls’ screenplay deftly bring the characters to the screen.

Within the first few moments, a man on a halting trans-Atlantic call – it’s 1982 and there were delays during such long-distance connections – delivers the news that Patrick’s father has died. Those pauses should be filled with sobs, gasps or at least contained shudders of shock. Instead, Patrick is trying hard to suppress giggles.

Is it because the heroin he injected moments before is coursing through his system? Certainly, but Patrick’s overjoyed and relieved that his father has kicked. Preparing to go to Manhattan, he has to clean up — or at least wash off the blood trickling down his arm from shooting up. Not since Roy Scheider portrayed Bob Fosse in “All that Jazz” has someone smoked so well in a shower.

With Cat Stevens’ “Wild World” as the ambient song — “Now that I’ve lost everything to you…” — the tone is perfectly set. It is going to be a bumpy flight, particularly for Patrick who’s intent on getting stoned as fast as possible.

His elation over his father’s death is curious. It’s not as if he grew up deprived; clearly, judging by his understated but superbly tailored clothes, Patrick is well-off. This is a hatred that goes far deeper than money, and while Patrick doesn’t bother to conceal his feelings – even from his father’s close friends – it isn’t until the second episode that we learn why.

On meeting his father David Melrose fleetingly, he seems charming, if one is an unquestioning and status-conscious Anglophile. To know him more intimately, though, proves tiresome, especially if anyone dared question his invariably correct opinions. To be his wife was disastrous. To be his son was nothing short of terrifying.

And it is in that dark corner of fear where young Patrick cowered.

David (Hugo Weaving) is a larger-than-life character. Cut off by his own father for wanting to be – horrors! – a composer and a physician, he married Eleanor (Jennifer Jason Leigh), an exceedingly rich American. She’s drunk most of the time, probably the only way to stay in this marriage (although it raises the question as to why stay). David, meanwhile, is too self-involved to notice, busy being a controlling megalomaniac, toying with people, roaring at them, but always in a plummy accent.

They are showy parts for actors, and both Leigh and Weaving clearly relish them.

So it’s hardly a drawback that the second episode, set in the South of France in 1967, focuses more on them than Cumberbatch. Beautifully designed and lit, the hour painfully illuminates Patrick’s wretched childhood. The terrific young Sebastian Maltz brings out all the hesitancy, loneliness and misery which filled the 9-year-old Patrick. It doesn’t take Sherlock Holmes to figure out why, 15 years later, Patrick has a serious drug habit.

With only the first two episodes available, and those being so different in tone and view – the second one harkens more to the nasty familial tensions and vicious verbal gymnastics of “Who’s Afraid of Virginia Woolf?” — it’s folly to guess how the others will unfold. Yet the pair deliver a solid promise that we are in for something very special.

And proof that, however harrowing they become, Cumberbatch will keep us watching.

Limited series. (Five episodes; two reviewed) Sat. May 12, 9 p.m.

TV Review: ‘Patrick Melrose,’ With Benedict Cumberbatch

CREW: Executive producers, Rachael Horovitz, Michael Jackson, Adam Ackland, Benedict Cumberbatch, Helen Flint

  • Crew: CAST: Benedict Cumberbatch, Jennifer Jason Leigh, Hugo Weaving, Philip Arditti, Gary Beadle, Elizabeth Berrington, Morfydd Clark, Nancy Crane, Blythe Danner