At the outbreak of the War Between the States, Maryland Calvert is loved by Maj. Alan Kendrick, son of a Virginia general, and Capt. Fulton Thorpe. Nancy, whom Thorpe has loved unwisely, follows him to Washington and commits suicide when she learns he will not marry her; as a result, Alan is forced to request his resignation. When Fort Sumter is fired upon, Alan, who admires Lincoln's principles, joins the Union Army though his father is among the Secessionist leaders; as a result, he is estranged from Maryland. Thorpe, who has joined the Confederacy as a spy, is responsible for Alan's arrest, but Maryland victoriously comes to his aid by ringing the alarm bell.
Unfortunately the movie The Heart of Maryland is not yet available on HBO Max.
| Camera | Hal Mohr | Director of Photography |
| Directing | D. Ross Lederman | Assistant Director |
| Writing | C. Graham Baker | Scenario Writer |
| Writing | David Belasco | Writer |
| Directing | Lloyd Bacon | Director |
