Never Let Me Go

One of the pleasures of writing a blog is the opportunity to use the titles of works you admire as titles of your posts. Of course, this can't be done arbitrarily; the title of each post must be relevant to its content. Today's title is in homage to Kazuo Ishiguro's superb science fiction novel "Never Let Me Go". Although Gargantua is in its infancy, I already have the very strong impression that one must keep one's gargantua at all costs, since it can end the game in a thunderbolt. I never want to let my gargantua go!

Puzzle of the day: how does White mate in one here?

update: here's the solution