A tightly wound technician at an insemination clinic creates a conflict of interest of absurd proportions when falls for a free-spirited client who's acting as a surrogate for her infertile sister. Without telling a soul -- not even Ariadna (Leticia Dolera), the woman he's impregnating -- lovesick hospital worker Serafín (Ernesto Alterio) uses his semen in the procedure, leading to hilarious complications in this delightful romantic comedy.