Wealthy businessman Charles Baskerville is chased by something and runs into the roadway, where he is promptly fatally smacked by a truck. His brother Henry suspects foul play was involved, so enlists Sherlock and Joan.
The two realize quickly that Charles was chased. Joan learns from a witness that whatever it was was large and glowed in the dark. Following death threats, they look to a genetics lab, which has a glow-in-the-dark dog, which in turn takes them to a paranoiac named Selden. Selden reveals Charles's penchant for patent-jacking.
Henry, being aware of the patent-jacking, could also be in danger. He is almost killed when the thing comes after him next. The thing is revelead to be a complex robot built out of those stolen patents, which are traced to a company owned by the Baskervilles' cousin, Roger Stapleton, who denies killing Charles.
With a clever ruse, the team reveals the true culprit as one of Stapleton's employees, Laura Lyons, who was a secret unknown Baskerville born in Australia.
Meanwhile, Sherlock grows concerned over the emotional turmoil suffered by Eugene, the medical examiner who was nearly killed by a bomb a month before. He convinces Eugene to take time off to recover emotionally from the experience.