Firstly, we’d urge you to steer clear of spoilers for this, the last ever episode of Spooks. Some media outlets have already given away a particularly tasty tidbit, which is a shame as this is an episode that, like revenge and Russian vodka, should be enjoyed cold.

Things look grim for Harry Pearce. Arrested over the death of Jim Coaver, beaten, and about to be extradited to the States and placed in the Pandorica that is the US detention system, it seems the Grid’s longest-serving member is set for an ignoble end. To make matters worse, we open with some particularly fervent Russian Nationalists (glimpsed earlier on in the series) planning a massive attack on London by way of a bomb on a plane. With its final episode, Spooks certainly sets itself plenty to contend with.

A neatly executed rescue mission proves to be the first of many highlights. It doesn’t take up much time, but that’s a good thing as there are more important issues to deal with. From then on the story becomes a claustrophobic game of cross and double-cross; of huge secrets revealed and even bigger lies told. Some are surprising, others you’ll probably have guessed already, but if you’ve invested in the Gavrik arc closely you won’t be disappointed with its culmination. It still has the capacity to shock.

This is the most character-focused finale we’ve ever had in the show’s ten-year history, more so even than the Lucas North plot last year. And although the stakes are literally sky-high, there’s barely anything in the way of the usual chasing around and shooting. The fate of nations hangs on what happens between a few people in one room; on whether they can trust one another through the decades-old deceptions, and the resulting tension bleeds through the screen. This is an episode which, for many characters, is all about who you can trust, and whether that trust and devotion have been fatally misplaced all along.

Everyone from the main cast to the guests are on top form. Jonathan Hyde, Alice Krige and Tom Weston-Jones have each excelled in their roles as the Gavrik family, and the finale sees their finest performances yet. Erin, Dimitri and Callum aren’t given much to do, but that’s unsurprising.

We’ve known the finale was going to be Harry’s episode since the start of the series – what we’ve really wanted to know was whether he’d go to the big Grid in the sky or emerge victorious. But after all this time in the game, what would victory for Harry even look like? Is it catching the bad guys and going home to a nice glass of scotch, or something as simple as making it to the end of the day alive?

Of course the question many will want answered is whether this final episode is a fitting send-off for the series and the show. Without giving anything away, the answer is a resounding yes.

No matter how long you’ve been watching the show you’ll be pleased. In its final hour, Spooks manages to encapsulate everything that has drawn audiences to the show over the past decade. We’re not even going to say what those things are for fear of giving anything away. You can probably guess yourself.

Just know that when that final negative flash comes, you won’t be disappointed. Drained maybe, but definitely not disappointed.

Airs at 9pm on Sunday 23rd October 2011 on BBC One.

> Order the Series 10 boxset on Amazon.

Are you looking forward to the final episode? Let us know below…