Bill Hickok, assisted by Calamity Jane, is after a foreign agent and his guerrilla band who are trying to take over some western territory just as the Civil War is coming to a close.

Best friends Kenneth Reynolds and Raymond Jordan are U.S. Navy officers, and Kenneth is engaged to Raymond's sister. But the eruption of the Civil War divides them, as Raymond stands by his native Virginia while Kenneth remains on duty as a Northern officer. Kenneth's uncle, John Ericsson, designs a new kind of ship, an ironclad he calls the Monitor. Eventually the war pits Kenneth, on board the Monitor, against his friend Raymond, serving aboard the South's own ironclad, the Merrimac (as it is called here). A naval battle ensues, one that will go down in history.

It's bad enough that Clarice Kendall Andrews, Paula's irresponsible sister, comes home from celebrating Mardi Gras and drunkenly mentions that she got married during the festivities. What's worse is the fact that Paula knows that Clarice is still married to an equally irresponsible gigolo. Paula learns that the man Clarice married, Stephen Cormack, is on his yacht and his lawyer, thinking that Paula is Clarice, offers the older woman $5000 to annul the marriage.