Monica Strömmerstedt

A dead and unknown woman is found in a canal. Police inspector Martin Beck becomes involved in the case. After several months the woman is identified. The police reconstruct the woman's last trip on the canal boat "Wilhelm Tham".

Inga, a 17 year-old, is sent to live with a scheming aunt who wants her to become mistress of her rich neighbour. She falls for a common young man instead.

A 19-year-old boy, after his mother's death, starts a relationship with his father's mistress, although he is engaged. The relationship continues after the woman has become his stepmother.