Reign by Katharine McGee

A queen’s life hangs in the balance, and her siblings’ decisions—about what to do, and most of all, who to love—could change the course of history. Romance. Duty. Power…only one can triumph in this stunning conclusion to the New York Times bestselling American Royals series.
America’s royal family is in shambles. Queen Beatrice is in a coma and Princess Samantha has gone missing—from the look of things, she ran away with her boyfriend, Lord Marshall Davis. Which means that Prince Jefferson is currently on the throne. For some in America, it’s exactly what they wanted: a King ruling the country. And for Daphne Deighton, who has tricked Jefferson into dating her again, it’s the ultimate dream come true.
Surely this is all just temporary. Won’t Beatrice wake up and reclaim her rightful place? Samantha can’t really be gone…can she? And Prince Jefferson will never truly be over his childhood crush, Nina Gonzalez. Right?

For the Washington family, the stakes are higher than ever. Love might save the throne….if secrets don’t destroy everything first.