Two modern best friends wake up in a rival kingdom as royal sisters sent into political marriages and secretly planted as spies. One weds the stoic war prince, and the other marries his charming, scheming brother. Both princes suspect betrayal. But the "elite spy" is a clueless bookworm, and the "naive girl" is a master strategist. As traps backfire and schemes unravel, suspicion turns into a sweet battle of wits and love.