The book belongs to the Bermuda cycle.
The context is the American War of Independence (thus the mid-eighteenth century) and the protagonist is Sir William, an English nobleman of French descent who has become a privateer to fight his half-brother, the cruel Marquis Halifax, who seeks to take his beloved from him.
Unhappy love and the grand poetry of the sea seem to be the novel’s points of reference:

ah! that night! embraced on the sand dunes, we listened to the sonorous rhythm of the waves.
It is a divine music, a music worth all those created by instruments of brass, of copper, of bronze

.
And at the beginning, one witnesses a naval battle, just as in Salgariʼs finest novels.
Subsequently, the plot takes another direction.
The beloved is held prisoner in Boston, a city in British hands and under siege by the Americans.
Sir William, together with his stalwarts, Testa di Pietra and Piccolo Fiocco, infiltrates the besieged city, and they attempt to free the woman.
A series of adventures follows, but in the end, the cruel Marquis of Halifax manages to escape with Sir Williamʼs beloved.

The narrative pace is sluggish, weighed down by the constant exchange of jokes and banter between Testa di Pietra and Piccolo Fiocco: dialogues dominate, relegating the action to the background.
On the other hand, the novel’s true protagonist is Testa di Pietra, his cunning, his peasant wisdom, his nostalgia for his native land.
Brittany.
Yet Salgari fails to depict sentiment.
Deprived of action and of characters who are both brooding and heroic, the narrative loses its allure and turns tedious.

Why not read it? The sea, love, and tragic destiny are nowhere to be found: the true Salgari, then, is absent.

The Corsairs of Bermuda