Short review. This is a good follow up to Once a Spy. A bit more action and a bit less reliance on Drummond (the Dad). If you have not heard of Once a Spy, it is a spy thriller about a super-spy that gets early onset Alzheimer's. His estranged son finds out his boring, appliance salesman is actually a spy. They both end up on the run from both the good guys (who want to take out the father to keep him from spilling secrets) and the bad guys (who want to find the secrets). Great original take on the spy story.
My long review of Twice a Spy on my blog http://bookwi.se/twice-a-spy/
(And the review of Once A Spy just for your info: http://bookwi.se/once-a-spy-by-keith-thomson/