Vera is married with a child but the relationship is humdrum and loveless and she is restless and bored, indulging her appetite for adventure and excitement through a series of flirtations, which sometimes go beyond the bounds of the socially acceptable.

Charlotte is a cowed drudge, suffering emotional abuse at the hands of her manipulative, brutal husband Geoffrey, who belittles and humiliates her in front of their three children.

The film shifts between the three households but its main focus is the way in which Lucy and Vera have to look on, unable to provide effective help despite their best attempts, as Charlotte's treatment by her husband (who, it is strongly implied, is also engaging in an unhealthy relationship with their elder daughter) becomes ever more shocking and she descends into alcoholism to blur her despair.

Unlike most of the hugely successful melodramas made by Gainsborough during the mid-1940s, They Were Sisters has a near-contemporary rather than a costume setting, spanning the years from the end of the First World War, to the late 1930s.

[5][6] According to Kinematograph Weekly the 'biggest winners' at the box office in 1945 Britain were The Seventh Veil, with "runners up" being (in release order), Madonna of the Seven Moons, Old Acquaintance, Frenchman's Creek, Mrs Parkington, Arsenic and Old Lace, Meet Me in St Louis, A Song to Remember, Since You Went Away, Here Come the Waves, Tonight and Every Night, Hollywood Canteen, They Were Sisters, The Princess and the Pirate, The Adventures of Susan, National Velvet, Mrs Skefflington, I Live in Grosvenor Square, Nob Hill, Perfect Strangers, Valley of Decision, Conflict and Duffy's Tavern.