Kilty Secrets by Amy Vansant

After discovering the shocking consequences of their lark in Las Vegas, Catriona and Broch find themselves on the hunt for a serial killer thought dead. Meanwhile, back in Hollywood, forces build against the time travelers as Catriona’s father endeavors to consolidate his burgeoning power. When his machinations capture the attention of a mysterious group of strangers, will they arrive to work with him or against him?
When a gorgeous redhead arrives promising help, Catriona and Broch must decided whether to trust her—a move that will irrevocably change the trajectory of their lives.