A young mathematician is shot with a 200-year-old bullet, inspiring wild theories by Castle about a time-traveling murderer. A tricked-out DeLorean and a suspect in Victorian clothing only adds to the notion. From the towers of Wall Street to an underground steampunk society, Castle and Beckett will journey to unravel the mystery. Victor Webster (as Beckett’s new boyfriend), Ken Baumann (as Alexis’ first boyfriend), and Eden Riegel (as the sister of the murder victim) guest star in the episode.
