This seems like a great place to ask: in the mid-2000s I encountered this series at my local library. It was a comic series printed on normal paper. About these 2 kids who would encounter weird things and constantly get sucked into the Underworld (or some other name). Everytime they made the trip down, they'd hear the song "Raindrops keep falling on my head". I think the first book had them escape from the Underworld via a trapdoor in a pharmacy, where they discovered Dr. Alucard was a vampire pretending to be a pharmacist.
I went back to that library 2 years ago and couldn't find it again, and my card had expired during the time they changed the system for a more modern one so I couldn't check my withdrawal records either. If any of you guys know it, lemme know.