Traveling from Zurich (Switzerland) to Danang (Vietnam) and transit in Hong Kong

Hi,
We are intending to travel from Zurich (Switzerland) to Danang (Vietnam) and might stop over in Hong Kong (arrival in HKG at 6:30 AM and departure at 18:05, the same day, my wife has a Vietnamese passport with Swiss resident permit (I am Swiss citizen), does she need a visa to visit Hong Kong city and back to airport (maybe for maximum 10 hrs) to continue our trip to Vietnam the same day?

Thanks and regards,