Nina and Anti Eirlys take a bus trip to Cardiff. But Anti Eirlys has soon made new friends and leaves Nina to chat to the bus driver, Marc Jones. It's the start of a romance. When Anti Eirlys dies suddenly, Nina becomes a rich woman and soon has a ring on her finger. One day, Marc disappears, and when Nina rings the bus company she is in for a shock.

Mae Nina yn mynd gydag Anti Eirlys ar drip bws. Mae Anti Eirlys yn gwneud ffrindiau gan adael Nina i sgwrsio efo'r gyrrwr, Marc Jones. Dyma ddechrau'r garwriaeth. Pan mae Anti Eirlys yn marw, mae'n gadael Nina yn fenyw gefnog ac o fewn dim mae modrwy ar ei bys. Un diwrnod, does dim golwg o Marc. Pan mae Nina'n ffonio'r cwmni bysus mae'n cael sioc a hanner.