Crossbones - Season 1 Episode 6 -

Balfour overhears Lowe confess to Kate of being an English spy sent to kill Blackbeard and he tells Selima, who sends pirates to find Lowe. Antoinette's torture continues at the hands of Jagger, now using Lowe's sketchbook as evidence that Edward "Blackbeard" Teach is alive. To comfort herself, she recites an encrypted rhyme. Jagger cracks the code - the chronometer Blackbeard sold to the Spanish will lead the fleet to a surprise attack from Blackbeard himself, the only one who knows where the Spaniards, and their treasure, will be.