Mysterious water leak into interior

Subject car is a 92 Integra GS, a 2-door coupe with a sunroof. When exposed to rain, the carpet on the right front area of the passenger cabin becomes damp or wet, depending on the amount of rain. Due to repeated occurrences, we now get a musty smell when it's damp. We have determined that no water is getting in from the bottom of the car; there are no holes on the floor. Also, the slopped part of the floor, the part extending up under the dashboard, gets wet. So, the leakage seems to be coming from somewhere right up toward the front of the passenger side and seeping down to the flat part of the floor.

My son thought perhaps water might be leaking in around the sunroof and somehow flowing down into the interior. No leaking around the sunroof has ever occurred on the under side of the roof. I have wondered whether water might be leaking in around the base of the windshield, perhaps from the water catch panel (don't know that actual terminology for it) that catches water running off the windshield, the panel that is visible at the base of the windshield with the hood open.

If we take this to a shop to have someone troubleshoot this, I think a body shop would appropriate for this type of problem.

Any comments on possible causes or how to troubleshoot this?

I have the exact same problem in my integra, I can see the water dripping down it comes from up above then collects on the floor mat. It comes in around the area above the passengers feet when it rains. I believe it is either the base of the windshield or something in that area. There is a piece of plastic there that is broken and something covered with tape but I havent had the time to look at it in detail. If I figure it out ill let you know, if you find anything please post about it.

Your son was actually right, the water gets in through the sunroof, which is in fact perfectly normal, thats why Honda engineers put 4 drain tubes there, which tend to pop off, therefore making water drip inside the car. Now lets get to the bad part, there are 2 drains at the front and 2 on the back, to get to the rear ones you need to just pop the plastic sides off, and on the driver side take the power antenna off. The fronts are a whole lot more complicated from what I understand as they run in the A-pillars and are hard to get too. If you start taking interior parts off you'll be able to find them and track down the leak. Perhaps pour some water into the right front corner of the sunroof.