There are many reasons to check out "Mission: Impossible — Rogue Nation," but one reason rises above all the rest: Rebecca Ferguson, the Swedish actress who makes her biggest big-screen appearance yet as suspicious spy Ilsa Faust.

Best known until now for her Golden Globe-nominated turn in "The White Queen," Ferguson lands with enormous impact here in "Mission: Impossible," playing quite easily the most fascinating character in the entire movie — and the most badass, too.

Here are seven reasons you'll worship Ilsa Faust by the time the "Rogue Nation" credits roll:

Her First Scene

Early on in the movie, Ethan Hunt finds himself in a deadly situation with no apparent escape. In walks Ferguson as Faust, literally holding the keys to Ethan's salvation in her hands. Will she help him, or will she just toss him further down the rabbit hole? It turns out, the two options aren't mutually exclusive, as her decision to save him only leads to bigger, darker questions.

The Grand Opera

Next time you see Ilsa, it's during a climactic opera scene in Vienna, easily the strongest sequence of the entire movie, and a contender for best "Mission: Impossible" scene of all time. Ilsa's role in the act is absolutely central, and she's involved in one of the most quietly intense standoffs in recent spy movie memory.

Swim For The Fences

Ilsa Faust is much more than a bikini babe, despite what this shot from the trailer might have you think. Let's just say that despite any differences they may have, she and Ethan can get along swimmingly, and leave it at that.

The Motorcycle Chase

Add to the list of awesome Ilsa Faust moments: the great "Rogue Nation" motorcycle chase, as Ilsa, Ethan, and a whole bunch of bad guys rip through the streets of Morocco, kicking up dirt, dodging bullets, and doing their damnedest not to crash and burn on the side of the road. Easier said than done.

The Climb

Like any great badass in an action movie, Ilsa Faust comes equipped with an amazing finishing move, seemingly ripped right out of "Mortal Kombat." On more than one occasion, you will watch as she climbs on top of her assailants, disarming or outright stab-stab-stabbing her way out of the situation. It's the best.

Whose Side Is She On?

Great question! And you'll be asking it all throughout "Rogue Nation," or at least most of it. You want Ilsa and Ethan to be true allies. But you also know there is a very, very, VERY real possibility that she's pulling his strings. Who does Ilsa really work for? What does she really want? Her hidden agenda is constantly at the crux of the character, and the suspicion we cast upon her is part of what makes her so intriguing — and I suspect that during a rewatch, knowing her TRUE motives will only make her more compelling.

The Bottom Line

Whether or not she's on the side of the angels, Ilsa Faust and Ethan Hunt have at least one thing in common: Both spies are outrageously talented in their respective fields, cool and confident under pressure, capable of seemingly superhuman feats of espionage excellence. Credit goes to the script, the stunt work, the direction — you name it — but most of all, credit to Rebecca Ferguson, who enters this well-established franchise in full multidimensional form, delivering one of the most complicated and alluring characters in the entire five film series. Long live Ilsa Faust. If we can't get her a spinoff movie of her own, then at least get Rebecca Ferguson an action franchise of her own. Hey, I hear Marvel's looking for a Captain Marvel…