After stopping a band of motorcycle thieves, a nano-virus is unleashed that attacks computers.  Mike has to stop this virus from spreading.  Sarah and her father meet up with her ex-boyfriend who is the one responsible for designing the virus.  KITT becomes infected and winds up killing Sarah's ex by accident.  He then inadvertently infects their base.  Now, with the base set to self destruct, Mike and Sarah must try to find out how to beat the encryption and install the antidote.