A new adventure of the Daltons, in which the famous bandits learn that they are... thunder! Our favorite Daltons vegetate in prison when the hand of fate comes knocking at their door! The dreadful desperados learn that they are thundering of a little boy whose they must temporarily provide education. Thank God, Lucky Luke is in charge of watching the Daltons and the unbearable bambin who only thinks about eating. But the inhabitants of Rupin City do not see with a very good eye the arrival of all these Daltons in their peaceful village.