Water Leak

We pushed the Duster outside just awhile ago and have a couple of good rains...and i discovered puddles on both floors. I don't see water getting around the windshield and I opened the air vents thinking the water may have come from there.

I my old british car days...stuff would get into the vent and clog a drain house causing a leak.. I cannot see one on this car.

where should I look and how can I test ?

Thanks
Grassy