When an art transporter is murdered and a priceless painting stolen, it's up to Castle to convince a woman with an extremely heightened sense of smell to help sniff out the killer in Castle Season 8 Episode 5. 

Watch Castle Season 8 Episode 5 Online

Not only does Mia's smelling abilities sideline Esposito and Ryan but the boys face even bigger challenges when only one of them passes the Sergeant's exam. Looks like Castle will only need one of those bottles of Champagne. 

And when Mia makes it clear that Beckett is still madly in love with Castle, will it change the course of this separation?

Find out when you watch Castle online here at TV Fanatic. 

C. Orlando was a TV Fanatic Staff Writer. Follow her on Twitter.