The Foot Soldiers

Beware of Russians bearing gifts...

...is the view at MI6 when a Russian agent presents himself to them in Denmark.

As a team assess his value, his former employers develop a brutal plan to show that no defector will ever be safe.

And they know where to find him. Which means there must be a mole in MI6.

So it is that the cavaliers of Six find themselves being interrogated by nondescript Jonas Merrick of Five - called back from retirement and his beloved caravan.

But while he may be grey, Jonas is also ruthless. As he works through the suspects in London, and violent mayhem breaks out in Denmark, Jonas will not just unmask a traitor, but hit back at the Russians with deadly force.