Dean is finding out that the mystery of his family's deaths could have a solution, but the cost is more than he is willing to pay.

The mysteries here on the ranch continue to mount, bringing his old partner from New York City to visit. Together, they are working on the mystery of Rex and Annie's past, along with revisiting the evidence in his case. Along the way, he starts to soften in his resolve to keep Lexi at arm's distance. He starts to enjoy life again when suddenly a twist he didn't see coming will suck the wind out of all their sails.

Lexi is doing her best to keep pace with Rex. He has good days and bad days. Staying a step ahead with ingenious ideas and ensuring Rex never leaves her sight is her recipe for success. A visit from her sister, though, Eric's arrival on the ranch and the growing mysteries surrounding the occupants' history here are distracting.

When she takes her eyes off the ball for one minute, it may spell certain doom for her favorite patient. Can they solve the mystery of Annie's past before Rex ends up paying the ultimate price?