Free short story promotion – 'One False Move'

Do free book promotions really work?
I have resisted taking part in Amazon's KDP Select programme, whereby an author makes a book exclusive to Amazon for a period when it is available in the Kindle lending library and can be offered free for a short period.
But I have written a Mike Delaney short story, a thriller to help promote my full-length thriller 'The Immortality Plot'.
It was an interesting experience, and a challenge, to compress a thriller plot into between 5-6,000 words. I realised how skilfull great short story writers like O.Henry and others really are.
You have to establish the personalities of the main characters, the obstacles and antagonists they have to overcome and battle with to reach a satisfying conclusion in the same amount of time and space as maybe two normal chapters.
In this short story, ex US government assassin, Hong Police officer and ex monk, Mike Delaney has just three hours to locate and rescue his friend and colleague Bob Messenger whose wheelchair has been connected to the national grid – a genuine electric chair.
If this 'sparks' your interest register by contacting me via the website to get the exact dates of the free promotion.