1777. Captain Isaac Biddlecomb, together with his wife and child, is bound for Philadelphia aboard the brig Charlemagne. His orders are to take command of the newly-built frigate Falmouth and take her out to sea before she is taken by General Richard Howe's invading army. Unknown to Biddlecomb, the entire British fleet stands between him and the new nation's capital. Forced to run his beloved brig aground, Biddlecomb comes face to face with his mortal enemy, Lieutenant John Smeaton. Meanwhile, General Washington has yielded Philadelphia to Britain's might. As Biddlecomb and his crew battle to reach the prized Falmouth, only shipwright Malachi Foote and a ragtag band of deserters stand between the vessel and the seemingly unstoppable British army.