The Enemy at Home - Conney C. M.

When Jack meets Brook, an English nurse, he’s certain she’s the woman for him. But war is no place for romance, and he doesn't have time to even learn her name before battle separates them. After months of searching with the help of their friends, Jack and Brook are reunited. He sends her to his home in Pennsylvania where he thinks she’ll be safe. But his brother, Edwin, has gone from hoping Jack will be killed in action to planning his murder. 
     Convinced the family’s holdings are rightfully his, Edwin decides he has to kill Brook too, and he thinks it’ll be easy. He’s already scared her away, and no one even knows she’s arrived.
     But the war ends before he can carry out his plan and now he’s in a race to beat his brother to Brook.
A race Jack doesn't know he's in—