Credit: ABC Family

With the Pretty Little Liars Season 4 summer season rushing to a close, it's time to start speculating in earnest about who Red Coat will turn out to be. We'll be examining our favorite suspects closely over the next few weeks, and today we'll start with one of the most suspicious characters on the show: Spencer's older sis, Melissa Hastings (Torrey DeVitto).

3 Reasons She's Suspicious

She's got the motive. There aren't actually that many characters who seem to having a convincing motive to spend so much energy torturing four teen girls, but Melissa does. Not only does she have reason to hate Ali and even her own sister (boyfriend stealers!), but she clearly knows a lot about what happened the summer before Ali's death (for instance, she hung out with CeCe, Ali, and Wilden), and she was there the night of Ali's disappearance. If one of Red Coat's main goals is to keep certain secrets about Ali under wraps, Melissa fits the bill.

Plus, Melissa being Red Coat would explain idiosyncrasies like "A" sometimes seeming to help the Liars — we'd totally buy that she's willing to torture her sis, but not, for instance, ready to allow her to die in a lodge fire.

She's got the means. The Hastings are rich, so it's not hard to believe that Melissa has some cash stashed away to help with the "A" operations. She's crazy smart, she's clearly ruthless, and she keeps disappearing at oh so convenient times (who's to say she's really off at an internship in England right now?). Melissa falls high on the small list of people who seems well equipped to pull off Red Coat's evil deeds.

It's all in the details. Pretty Little Liars isn't just about the big picture — small clues matter too, and Melissa has more than a few pointing in her direction. For instance, she's on the short list of characters we know play the piano (like "A" did in the Episode 9 tag), there's the whole toffee thing that some fans read a lot into, she's spent a lot of time in Philly, which is where the PO Box Toby learned about is located, she knows about the mask maker ... the list goes on.

Why It Might Not Be Melissa

So, she's got the means and motive, and there are enough clues to suggest Spencer's older sis could be the ultimate big bad. So, why isn't everyone sure Melissa is the culprit? Well, for one thing she's been a suspect one too many time. At this point, Melissa being Red Coat seems a little too obvious. And we'll admit it: We bought her confession in Season 4, Episode 4: "Face Time." Clearly, she's deep into this thing, and she's very high on our list of suspects in Wilden's murder, but in the end, we've seen her display enough twisted affection towards Spencer that we just can't quite see her as the architect of her sister's pain.

What do you think: Could Melissa be Red Coat, or is she off the table as a suspect in your mind?

Find more Pretty Little Liars spoilers here.

Catch the next episode of Pretty Little Liars on Tuesday, August 13, 2013 at 8 p.m. ET/PT on ABC Family.