Tweed is faced with an unexpected deadly new enemy - an adversary from the West. Paula Grey is plunged into a life-or-death situation in faraway Lapland. Bob Newman experiences personal tragedy at dawn in Suffolk, is determined on revenge. Are these events linked?

Europe faces chaos - organised by the invisible army using new methods to take over the continent. Action sweeps from England across Scandinavia as Tweed's team struggles to destroy an evil force.

What part is played by devious Peggy Vanderheld, by Evelyn Lennox, sister of Newman's girlfriend, by Franklin D. Hauser, owner of INCUBUS, the world's largest bank? Who is the secret killer eliminating, one by one, witnesses sought by Tweed?

The climax - the surge of the whirlpool - is as explosive as only Colin Forbes can make it.