Today's Amazon.co.uk Big Deal is 18 books from Andrea Camilleri's Commisario Montalbano series:
https://www.amazon.co.uk/b?node=4725112031
It includes the following:
#4: The Voice of the Violin
#5: Excursion to Tindari
#6: The Scent of the Night
#7: Rounding the Mark
#9: The Paper Moon
#10: August Heat
#11: The Wings of the Sphinx
#12: The Track of Sand
#14: The Age of Doubt
#15: The Dance of the Seagull
#16: The Treasure Hunt
#17: Angelica's Smile
#18: Game of Mirrors
#19: Blade of Light
#20: A Voice in the Night
#21: A Nest of Vipers
#22: The Pyramid of Mud
#23: The Overnight Kidnapper
Note that many of these are repeats; new (to me today) were #18, #19 and #23, and #22 turned up earlier this week so may be new to others. That now means only the last 4 in the series haven't yet been reduced; #24 & #25 have been translated, #26 is not yet released, & #27 isn't available in English yet.