A Russian immigrant and mother of two vanishes from her Kentucky home, leaving behind a hidden diary, secret recordings, and cryptic evidence that point to her college professor husband. Detective Jason Friend must unravel lies, affair accusations, and a suspicious heart rate spike to prove the beloved teacher killed his wife—without her body. Ella Jackson's Fitbit data showed a sudden heart rate spike at 6:15 p.m. on the day she disappeared, then stopped abruptly, suggesting she died in Glenn's home while he claimed to be at the dog park.