The once and future Malcom Reynolds??By Marc Bernardin, Source:

The once and future Malcolm Reynolds has never shied away from dropping little tributes to Joss Whedon’s late, lamented sci-fi western in his current gig on ABC’s hit cop show. But now he’s going to bring more than an old costume … he’s bringing an old cast member.

Since he’s no longer busy grunting at nerds, spies and nerd-spies, Adam Baldwin is going to drop by Castle and Beckett’s precinct for a guest spot playing a cop named Ethan Slaughter. (Of course, that’s his name. I wonder if he was also a sergeant in the Marines before joining the force.)

Anyway, Slaughter is described by TV Guide as:

a rough and tumble cop from the city’s gang unit who lands a case that Castle is desperate to follow. Along the way, Slaughter shows Castle a dirtier side of police work that forces Castle to reconsider what he’s willing to do to close a case. As the season nears its cliffhanging conclusion, expect this new alliance to place Castle in the line of fire like never before.

I will bet a dozen donuts that, at some point during the episode, the former Jayne Cobb with say the following to the former Capt. Mal: “My days of not taking you seriously are certainly coming to a middle.”