Rudolf Buth, 86, leaves his 45-year-old apartment due to loneliness and moves in with Pauline Pappert and Therese Heinze, also 86, who have lived together for ten years. Initially, their different lifestyles clash, but the women win Rudolf over with empathy. Rudolf charms them, with Therese feeling the need to educate him and Pauline enjoying flirting. However, their joy is short-lived. The documentary “Ménage à trois” captures their story of finding companionship in old age.