1864. The USS Kearsarge, a Union warship, puts in at the port of Amsterdam. Its mission in Europe: to stop the predations of the Alabama, a confederate privateer that's been preying on the transatlantic trade. Aboard are Blutch and Chesterfield, threatened with a firing squad by an irascible general, and sent to lie low in the Navy by their own superiors. Soon, the Alabama is spotted, and the Union ship rushes to intercept it. The confrontation will take place in the English Channel!