Smokestack @2 + Flagstones question

[Gambit]

I have a smokestack set at 2, can I sac flagstones and then sac the tapped plains I bring into play with it? Or does the entire smokestack effect need to be paid before the flagstones would fetch? I was pretty much under the impression that it was legal, but I'd like to know officially.

Thanks.

[Sanguine Voyeur]

The triggered ability from Flagstones doesn't go on the stack until after the Smokestack trigger finished resolving. You wouldn't get to sacrifice the tapped Plains that turn.