Karin does not belong to the nobility but nevertheless marries the mentally ill king Erik XIV and becomes queen of Sweden. The king's skilled counsellor Gran Persson wants a royal policy supporting the people and supported by it. But in relation to the nobility the king oscillates between provocative strength and unpredictable weakness. Gran arranges that some very powerful noblemen are killed. Subsequently the king tries to have them convicted of high treason by the parliament. He forgets the manuscript, mixes up all facts, and the noblemen are acquitted. But Gran speedily gathers another parliament and has them convicted. Meanwhile Erik apologises because of the unjust murders. Hence Erik is dethroned and imprisoned. Gran is executed. Karin is restricted to a castle in Finland. In the prison Erik believes that he is still the king and gives the guards presents such as all fishes in the Baltic Sea.