The secret came out on Pretty Little Liars last night, as Spencer now knows the very troubling truth about Toby. How will she respond to the devastating connection between her boyfriend and Mona?

By acting very strangely, that much is evident based on the following clip from next Tuesday's "Out of the Frying Pan, Into the Inferno." Watch Spencer react - or NOT react - to Emily's latest discovery in this sneak peek:

She'll also come across as aloof when strolling with Aria and Hanna, who are both sharing their own boyfriend problems in the following scene. But little do that know what a boyfriend problem can actually be...

Finally, the gals appear to stumble on a major clue. And, yes, it's related to Toby. Watch now and prepare for another intense hour of mystery and suspense on January 29:

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.