'Happy Endings' video: Mark-Paul Gosselaar returns for revenge in 'Un-sabotageable'

How do you ruin a life that has nowhere to go but up? That's the question faced by "Happy Enddings" when old roommate, Chase (returning guest star Mark-Paul Gosselaar), returns to sabotage Max's ( Adam Pally) life.

But is Max really "Un-sabotageable"?

You may recall the ultra-perfect Chase from his first appearance on the Season 3 episode, "The Ex-Factor." Max was initially thrilled at the new guy, whose functional lifestyle meant that the apartment got furniture and gadget upgrades. Things quickly fell apart, however, when Chase suddenly disappeared, leading the gang to pry into the man's private life.

The results were not pretty.

Now, Chase is back. And it seems like the events of "The Ex-Factor" have had a negative impact on the poor guy's life. He still doesn't have a job. Chase doesn't even have a girlfriend now, because she's about to marry his brother.

For obvious and not-entirely-false reasons, Chase blames Max for this.

Unfortunately, this is Max we're talking about. What can be done to the guy that he hasn't already done to himself? Chase leaves his initial confrontation with the ex-roommate seemingly frustrated. But what if Chase does find a way to hurt Max? Can it be done?

We will find out when "Un-sabotageable" airs on Friday, April 26 at 8:30pm on ABC.

Photo/Video credit: ABC