Day X / Whole series of 5 books

Day X is a series of 5 publications, each featuring a one-day collaboration between a writer and a photographer working in Europe.
Buy all 4 already existing books of the series plus books number 5, to be published in Spring 2019.  Who the the authors will be is a surprise. 
Receive the first 4 books now and the 5th as soon as its ready, hot off the press.