Gan fod Myfi ar drothwy ei phen blwydd yn 80 oed mae ei phlant, Delyth a Robin, yn penderfynu trefnu parti syrpréis iddi. Ond sut mae gwneud hynny heb ffraeo, gan fod gwraig Robin yn mynnu rhoi ei phig i mewn, a merch Delyth wastad yn tynnu'n groes?
Delyth and Robin decide to arrange a surprise 80th birthday party for their mother, Myfi. But how will they succeed without quarrelling, when Robin's wife is determined to have her say, and Delyth's daughter is always contrary?
