Diann Hoelscher, 39, seemingly had it all: She was beautiful, had two adorable children, an adoring husband and a clothing design business. On February 4, 1986, Diann drove from her San Antonio home to Houston to sell some of her high-end fabrics, but she never made it back. On February 13, Diann's husband, Joseph, reported his wife missing. The same day, 30 miles outside Houston, a witness saw a man in a red-and-white pickup truck throw Diann's briefcase into a drainage ditch in an oil field. Three months later, Diann's vehicle was found abandoned in a mall parking lot in Houston. As the years went by, Diann's family and friends began to accept that they might never find out what happened, and the case went cold. That changed in December 2013, when the University of North Texas used DNA testing to confirm that an unidentified skeleton, found in 1997, was Diann. With the discovery of her body, interest in the nearly 30-year-old case was reignited, with Lieutenant Heather Owens of the Waller County Sheriff's Office taking the lead. The tenacious investigator refuses to let this case fall by the wayside and is determined to put Diann's killer behind bars.