I began playing with the idea of 'The Bid' - the 2nd Gonzales & Vaslik thriller/mystery, back in 2015. The plot is about terrorists using small drones or UAVs to make a strike at the US president.
I researched the subject and got a pretty good idea of the capabilities and limits of the kind of drones available then used as a leisure pursuit, and other, more commercial uses, for land and pipeline surveys, traffic monitoring, big game watching and film footage. It was and is a fascinating subject.
But the thing I was very quickly reminded about was that technology never stands still. And the limits I had written about soon got busted wide open.
You can read a piece I wrote on this issue for Shots Magazine right here: http://www.shotsmag.co.uk/feature_view.aspx?FEATURE_ID=334
'The Bid' - Midnight Ink Books - available in p/b and ebook.