Colonel Peter Challinor threatens to wipe out hundreds, possibly thousands, of residents on the Isle of Man using the most toxic nerve agent ever synthesized. The hunt is on to find him and stop him, but time is short and there are plenty of places to hide. Hugh Bottomley arrives from the Ministry of Defence in London to help out where he can. But Sparky knows Bottomley’s past, and it is one that Bottomley wouldn’t like the public to be made aware of. Meanwhile, house-to-house enquiries turn up more than a toxic nerve agent, and the arrival of Rolien van der Laan does nothing to simplify an increasingly complex situation. It’s bound to end in tears.