Confused by Fringe's tangled mysteries and universe-spanning weirdness? You should definitely check out tonight's episode, which finally makes sense of some of the show's long-standing questions. Plus, it's actually an emotionally powerful hour of television, in which the show's main characters are put through the wringer — and nobody's quite the same afterwards.

Without giving too much away, this episode gives us some major answers about the Observers and exactly where they come from — and also, some major hints about why they're so interested in Peter in particular. But also, some dots from the show's first two seasons are connected up in some unexpected ways, especially as regards Olivia and her special powers.

And most of all, you get a firm sense of what this show is really about — something that hasn't always been the case. By the end of tonight's tear-jerking episode, you're left with no doubt of the centrality of the Peter-Olivia relationship to the show's future.

Speaking of which, the show's producers were on a conference call with reporters yesterday and they mentioned once again that they plan to have a fourth season finale that can also serve as a satisfying series finale — if the show really doesn't get a fifth season, after all. (Current rumors suggest the show might get a shorter final season, along the lines of what Chuck just had. Fingers crossed.) With the show laying out more of its mythology and stronger thematic lines, it's easier to have confidence that one way or the other, we're really going to get some excellent closure here.

All in all, tonight's episode is a must-watch for anyone who's followed Fringe at any point in the past.