No one's ever paid much attention to Emily Wentworth, but all that changes in the spring of 1918 when her twin brother is reported missing and presumed killed in what is supposed to be the war to end all wars. Emily's convinced that Theo is alive and travels to France to find him. Since no one would let her go if they knew of her mission, she capitalizes on her ability to drive and repair a Model T and signs on as an ambulance driver. Emily is determined to reach Theo, even if it means allying herself with Grant Randall, a reporter who writes beautifully but appears oddly unaffected by the war. She enlists Grant's aid, promising to keep his breakdown-prone Model T running if he'll help her find her brother. For his part, though he's intrigued by the beautiful woman who's so skilled at what many would consider a man's work, Grant knows better than to let himself care too deeply about Emily's mission. After all, caring is the road to heartache. Though each have reservations, they embark on a journey fraught with danger. As they make their way across the war-torn countryside, Grant encourages Emily to keep her fears at bay by whistling in the dark. Emily realizes Grant has fears of his own, fears that threaten both his happiness and hers. Can Emily help him overcome his fears before its too late?