A young amnesiac and terribly clumsy woman must rely on the help of a strange psychologist to remember that she is a super heroine who holds the key to stop a mad scientist who's about to attempt a quantum experiment that could destroy humanity.

Agree with Valentin that the concept might work better as a comedy.

I think that the concept of an amnesiac super heroine works better as a sitcom.
30 minutes episode in which she must save the world. Every day her friends have to convince her that she is a super heroine and she has super power. Obviously she initially does not believe them and think that THEY are crazy. Because she will use her power when she is in danger or sense somebody she cares is in danger, her friends have then to do all sort of things to force her to use her power. Once convinced that she has super power, instead of trying to save earth, she could be very shallow and try to abuse her power (shopping, ...).
She needs to have a kryptonite that the heroine would be attracted to: Cake, red shoes, ...
Using the usual sitcom archetype characters:
The square: she is the square character or the personality she has are.
The wisecracker: slacker who uses the fact that she is amnesiac to not pay his due and financially exploit the situation. Maybe a family member, a brother/sister/cousin.
The bully: the stupid baddy who tries to take over the world and always fail. The baddy secretly hope that they would be BFF. Most of his plan then backfire against him/her.
The Dork/Geek: the one who tries to solve the solution. Has read all the books on amnesia or personality disorder. Usually knows the answer, but nobody listen to him. Often save the day, but somebody else take credit for it.
The Goofball: the out there character. Think Phoebe in Friends, Kramer in Seinfeld, Daphne in Frasier.

Hi Bomarc

I found this draft of the logline confusing. I understand what your trying to do with focusing on "...the situation..." but in my mind this is the wrong approach for a logline.

In my opinion good loglines start with;
when a something happens to a someone that is of this description, they have to do this...
or
when a someone of this description has this thing happen to them they have to do this...

This draft has;
when a someone (MC) of this description (super hero) and this description (amnesiac) after that thing (accident) during that other thing (on a mission) has this thing happen to them (become a patient of a shrink) with this description (personality disorder) for this reason (retrieve her memory) description of the world (not safe place).

In short this logline doesn't describe a story rather elements in the plot and setting. Karel Segers has a good little formula that helps with the basic structure of a logline here it is:
When a {major event} happens {the MC} must {do the main action} and learn to {over come the flaw}.
If the way they overcome the flaw is significant then add that into the logline as well.