Benedict Cumberbatch delivers a captivating performance as Patrick Melrose

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Patrick Melrose is the creation of writer Edward St Aubyn, whose five semi-autobiographical novels have now become a five-part Sky Atlantic drama adapted by One Day's David Nicholls. Each book gets its own episode across the decades of Melrose's life.

As the trauma-afflicted and drug-addicted Melrose, Cumberbatch is cut loose in a way we've never quite seen before, shedding all that reserve. Put simply, he's a hot mess.

But even if this is a bit of a departure from the uptight and controlled roles we normally see him play, it's still classic Cumberbatch. There is something deeply familiar about Melrose's idiosyncratic manner of speaking and the way he casts off social conventions and makes the people around him uncomfortable.

And it works so well. The first instalment is fantastically funny as well as deeply tragic, Cumberbatch is perfectly cast, and if all the episodes are this good we are in for quite a ride.

So Melrose travels to New York to collect the source of his childhood trauma, i.e. his deceased and detested dad who is now confined to a little wooden box. But daddy dearest's legacy hasn't gone away. Despite Melrose's best intentions of going cold turkey, he is soon searching the streets of Manhattan for whatever drugs he can find.

Be warned: this first episode is INTENSE. Over the course of the hour, Melrose quits heroin, compensates with (un)healthy quantities of alcohol and cocaine and pills, and then un-quits heroin when he can bear it no longer.

He races through withdrawal and bingeing and withdrawal at breakneck speed. This is not a show for the needle-phobic. He covers the hotel room in coke, bathes in whisky (no Champagne baths for Melrose), hurls his father's ashes around the room, and contemplates the fall from the hotel room's windows.

How can a tale of an addiction rooted in childhood trauma be so fun to watch? Well, even the voices in Melrose's head are witty and entertaining. Perhaps it's the way Melrose puts people on edge as he yells at this inner monologue in a fancy restaurant or shakes his way through withdrawal in the back of a taxi. Perhaps it's the sharp dialogue. Perhaps it's the flashes of self-awareness and self-parody.

Even if you can guess at the source of his trauma, and even if the flashbacks of little kid Patrick shaking as he walks to his father's bedroom door give you a dark inking of his demons, the evil is not yet named. It lurks beneath the surface, poisoning Melrose's adulthood. It cannot be spoken of or acknowledged. His inner voice says: repress it! Push it down! Take more drugs!

Considering his villain of a father (Hugo Weaving) and his quietly complicit mother Eleanor Melrose (Jennifer Jason Leigh), you have a lot of sympathy for Melrose as a character. But he's also kind of awful: selfish and self-obsessed and entitled.

So far we have talked about Cumberbatch, Cumberbatch, Cumberbatch. That's because this is almost a one-man show. Melrose the addict is at the centre of his own universe and the whole drama rests on his shoulders, whether he is completely off his face on heroin or sweating with withdrawal pangs or babbling on cocaine. Few supporting characters get much screen-time.

But we do get to see Allison Williams as the wonderful Marianne, his sweet girlfriend's New York pal who agrees to see him for dinner, even though the last time they met he passed out in the toilet and went blue.

Having spent the dinner slurping Martinis like a sloppy Bond and making asides to the box of his father's ashes occupying the third seat at the table, Melrose makes a desperate pass in her direction. He needs her, he wants her – but she owes him nothing and she knows it. So long Marianne!

The only oddity in the first episode is that Melrose is meant to be 22. No offence to 41-year-old Cumberbatch, but he does not look 22 any more. Perhaps Melrose's binges have left him prematurely aged?

Still – at least the young man will grow into his middle-aged looks in later episodes. And after this hugely impressive opening episode we definitely can't wait to catch up with Patrick Melrose for the next chapter of his life.

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