In complete contrast to her mastery of the lake, professional fisherwoman, Rosa (Nele Rosetz), struggles to keep her head above water when interacting with her career-swamped partner, architect Kirsten (Therese Haemer). It's not all plain sailing for the couple whose relationship seems all the more strained due to Kirsten's failure to fully commit to Rosa (a bitter ex-husband and distant son add to the burden). Changing tides mark the unexpected arrival of a younger lesbian couple on the lake. After an initial sore encounter with Rosa (over a stolen fish), dancer Evi (Lea Draeger) and veterinary student Olivia (Constanze Wächter) are welcomed into the couple's lakeside home. As the two couples become more acquainted (over wine, weed and synchronized yoga), each woman becomes all too aware that there are plenty more fish in the sea. As darkness falls and loyalties wane, the pressure mounts, so much so that it becomes unclear whether murder or an ménage à quatre is on the cards.