After making early gains on the battlefields, General Washington's struggling young armies are being relentlessly pressed back by British troops and Hessian mercenaries. Among the enemy's ranks is a mysterious force from the Covenant, a secret society of evil witches that for centuries has been pulling the strings of European history: a Hessian necromancer who drinks the power of other witches like a vampire and whose allies include devils and ghosts. Now this man seeks to sap the fighting spirit of Washington's troops by means of a pernicious curse, chaining the souls of the dead to the spirits of the living.

Against him stand Proctor Brown and Deborah Walcott, two young patriots who lead a ragtag band of witches as much in danger from their own side as from the enemy. Proctor and Deborah must find a way to break the Hessian's curse before the newborn revolution is smothered in its cradle - and the Covenant extends its dark dominion to the shores of America, extinguishing forever the already sputtering torch of liberty.