It is a moment before dawn, and the river traffic on the Thames begins to ease its way through the fog. The River police find the body of a young girl left dry by the ebb tide. Her body is brought ashore and her possessions examined. Who is she? And what drove her to take her own life?

For the young married couple (Judi Dench and Norman Rodway) love brought them together, but now marriage and a child have driven them apart. The young husband would rather stay out than return home to a wife kept awake by a teething baby daughter. Their story is witnesses by their friend (Joe Melia), a bachelor, who is exposed as the loneliest of them all.