Crabtree and John are transporting a convicted axe murderer to prison when she escapes to exact revenge on those who testified against her.

Inventor Nikola Tesla assists Murdoch in an investigation into the death of a man experimenting with invisibility.

After the release of Murdoch and Ogden's book, a series of copycat murders begin to take place.

Murdoch learns from Terence Meyers that James Pendrick has been abducted and the inventor's life is in danger.