"Now entering their third year on the job, the rookies have learned to overcome the sophomore curse - that a little knowledge is a dangerous thing," she tells us.
"With a little more experience under their belts, they're starting to realise that the uniform that's shaping their professional identity has also started to shape them as people.
"They're also starting to learn that sometimes, in order to define who you are, you must first sacrifice who you used to be… even if you're still figuring that out."
She adds: "Every year the characters struggle and grow and it's completely relatable regardless of how much you've seen. This isn't a procedural like other cop shows."
Missy also tells us that she's been through training with real life police officers to ensure the show is as authentic as possible.
"Before we started filming season one, a couple officers taught us the ins and outs of handling our guns, how to approach a dangerous person, etc.," she says. "Throughout the last three years, I have been speaking with the on set officers and asking questions to help with character situations. I haven't gone on a ride along, but some people have on our show."
The first episode of the third season saw Star Trek legend William Shatner joining the cast as a drunk driver responsible for a car accident involving multiple cars.
Missy tells us that although she didn't get to work for too long with William, she loved having him on set. "I only worked with William Shatner for a couple hours, our storylines didn't coincide very much. However, I had a great time watching him punch Dov [Epstein] out and then whispering under my breath, 'Oh Shat!'"
We also wanted to know more about Missy outside Rookie Blue so we asked her a few of our Getting To Know questions...
I'm happiest when... I'm with my family
The last time I cried was... 5 minutes ago.
In ten years I'd like to be... a mother.
The person I want to work with the most is... Sandra Bullock
My friends would describe me as... weird.
The part of me I like the least is... Well, I'm trying to accept all of me, but sometimes I have a hard time with how sensitive I can be.
My hero is... I don't have a specific hero but there are a lot of people in my life who inspire me in different ways. I'm always learning from someone. However my little sister is suggesting herself at this moment.
The best piece of advice I've been given is... One of quotes I like is "Be who you are and say what you mean, because those who mind don't matter and those who matter don't mind. " Dr. Seuss
My guilty pleasure is... McDonalds – there's just something about their ammonia dipped meat that gets me every time. Seriously. I love Big Macs.
Season three of Rookie Blue airs Sunday's at 9pm on Universal
Are you a fan of Rookie Blue? Let us know below!
Dallas! We meet the new cast including hot Jesse Metcalfe!
Sabrina The Teenage WItch: Where are they now?
Text Santa, the star-studded charity initiative, is back this year