As the Civil War unfolds, Emilia and Thomas, now part of the 28th Massachusetts regiment, are thrust into the brutal reality of battle. Their bonds are tested, and Emilia is torn between her growing adoration for Thomas and her desire to prove herself. She must decide whether to push the overbearing Irishman away or accept they need each other more than they realize. Making matters worse, unknown threats start targeting the Romani lass, turning the seemingly innocent choice into a possibly fatal one.

Meanwhile, on Boston's home front, Shay and Michael's lives intertwine with a frequency that borders on maddening. As Michael starts working with Pierre, the enigmatic southerner in their city, things take a positive turn. However, tensions escalate, and threats emerge shortly after, causing Michael to question the Rebel's intentions. Shay and Michael's survival hinges on overcoming grudges and unwanted, if not increasingly heated, feelings.

After all, the threat to Emilia may soon be at their own doorstep.

Emilia and Shay may have found the vials that could transport them back to the 21st century, but the question remains: will they find their way back, or will they risk losing far more than their hearts?