The Jolley-Rogers, who seemed to finally be doing so well among the landlubbers, are suddenly talking gibberish! Matilda does not understand Jim anymore! Is that a case of Pirate Black Fever? Mrs. Bevan certainly thinks so, and spreads the rumour of an epidemic. For her part, Matilda finds out it’s only the « Pirate Private Parley Day »: the Jolley-Rogers are celebrating their roots, by talking only with «Arrrrr!» It’s quite funny and easy to learn. But by now, the town is in a state of emergency: because of Bevan’s rumours, panic has seized everyone, and soon the inhabitants, who fear they’ll be contaminated by the Black Fever, gather with pitchforks to expel the pirates. How are Matilda and Jim going to save the situation, calm everyone and not sell pirate traditions short?