‘Secrets are weird,’ Ephra Stein (Andrew Buchan) tells sister Nessa (Maggie Gyllenhaal). ‘People think you share them – but you don’t.’

Not if you’re a selfish, narcissistic, emotionally-stunted handpump hopelessly in thrall to the Israeli government, MI5 and your own penis, perhaps. But if you’re the best British drama series of 2014 (note to Hugo Blick: start prepping those acceptance speeches for next year’s award seasons), the secrets that sustain the suspense can only be kept under wraps for so long. At some point, the truth – or some of the truth – must be allowed to seep out. Leave people in the dark for too long and eventually they lose interest in the light.

On the other hand, you have to keep some things back to ensure the audience remains hungry. ‘Make ‘em wait,’ as Wilkie Collins famously put it, and balancing the drip-feeding of details with the need to maintain the dramatic tension is a delicate task.

In a show without loose ends (‘It’s all connected,’ Sir Hugh Hayden-Hoyle says to Ephra: ‘Your sister’s kidnapping, the child’s kidnapping, your academy … I even think Samir Meshal’s suicide is in there somewhere’), giving away the wrong information at the wrong time could bring the whole edifice crashing down on our unworthy heads.

That’s why, for example, Blick has revealed the truth about Kasim’s parentage without explaining why he was abducted: to keep us agog. Similarly, we’re gradually discovering how compromised the Stein Group has become but still waiting to learn the true extent of Shlomo Zahari’s corruption – although it’s unlikely to be a coincidence that he’s shown wearing Devil horns to scare Ephra’s kids. ‘The monster is coming back,’ he roars.

Meanwhile, MI5 has its own sane monsters dishing out devilry to keep the British flag flying. Monica Chatwin (Eve Best), soon to replace Sir HHH as the Head of the Middle East desk, is as demure and softly-spoken as a choirgirl, yet her balls are pure titanium. Back in the day, she demanded Ephra step aside to allow his sister to take over the family business; more recently, she spread enough disinformation about Shlomo’s fictional Hezbollah connections to prevent him getting the cable-laying contract he was expecting. And why?

‘Because if the world finds out what Shlomo Zahari has done, you’ll be ruined,’ Monica explains to Nessa. Shortly afterwards, more of the ugly truth materialises: cables inter-territory cables laid by the Stein Group have been tapped, a sniffer device attached to intercept all outgoing phone calls from the West Bank.

The monitoring station is in the Stein Group’s academy in Tel Aviv, and when stereotypically scruffy computer studies professor and classic single episode-character Shimon Ben Reuven (Uriel Emil) finds it, he ends up stabbed and chucked in a dumpster.

The tracking computers are switched off, but it’s too late: The Honourable Woman’s surface has been broken and the facts are gradually being exhumed. Appropriately, the most memorable (not to mention ominous) image of the episode is a flashback to the original cable-laying back in 2004. Excavators tear up great chunks of earth, revealing what lies beneath.

Any programme that can make a scene of JCBs digging up an anonymous patch of barren land as captivating as captivating as the back alley murder of a university professor and the rescue of hostages by paratroopers is deserving of the highest praise.

Airs at 9pm on Thursday 31 July 2014 on BBC Two.

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