Time of the Warlord by Ivy Hollins

A woman on a mission. A medieval warlord with a secret. A time travel mystery that spans centuries…

Sadie is determined to find the truth about her missing twin sister – and all the evidence points to a stone circle on the island of Arran. One touch of the stone, and Sadie finds herself flung back through time, straight into the arms of powerful warlord Ciaran. She needs to get away, needs to find the truth about her sister – but what if Ciaran knows more than he’s willing to reveal?
After years of service to his king, Ciaran just wants to enjoy his new role as lord of his own lands. Loyalty is a hard habit to break, though, and Ciaran still has a lot of secrets to keep. The last thing he needs is a beautiful, seductive woman working to undermine everything he’s worked for – but Sadie is hard to resist…

Book 5 in the Stones of Scotland series, this time travel romance is set in Celtic Scotland. Read as a standalone romance, or as part of the bigger mystery that makes up the Stones of Scotland series.