Doctor Who Dark Water Review

Huh? What?

Wha, wha, what just happened? Missy is the master!!!!!!! One of the doctor's resilient enemies has found her way back into the doctor's life. And has changed gender, never before has a time lord proved that the result of their regeneration could literally be anything. It was spectacular to see an incarnation of one of my favourite villians in such a stark contrast to their predessors- it literally blew my mind. 
Michelle Gomez brings so much snappy and playfulness to her performance that I felt the master was actually enjoying being a female and wanted to bath in the doctor's helpless and blind sighted vision.
So as the beginning of episodes go, my heart was abruptly ripped out of my chest as Danny was tragically killed in a traffic accident. This felt very far from the Who universe as a central character was taken from the audience in such ordinary circumstances.
A very heroic and selfless act for Danny was when he kept telling Clara he loved her to make her believe that he wasn't himself so that in turn she would get to live. That moment was for me the core of who his character is. I hope in some form in does survive.
A very disturbing explanation about what happens to you when you die felt very hideous when it was stripped down and emphasised through those three words. That the dead are still conscious as their previous bodies are horridly undertaken under the knife or thrown into a torrent of flames is mind numblingly terrifying.
However, the complex thought and decision that has been compiled together is astounding and enormously thought provoking and grips the eyes to the screen as if they were magnets. 
Clara is pulled through into a mess of emotions that sees her betraying the doctor by thinking she can persuade the doctor to bring Danny back if she throws all of his TARDIS keys into an ocean of lava was groundbreaking concerning their relationship. But, oh it's only a dream which the doctor conducted to see how far Clara would take the situation. I think this could have influenced the doctor to decide to help Clara bring Danny back and is in a moment a glimpse into Capaldi's doctor showing a slice of compassion towards his friend.
The applauling realisation that these cybermen are in fact people who have died is a dreadful thing to have to comprehend.
Now this episode is very dark but not without some cracking humour filled scenes; Missy kissing the doctor, the doctor oblivious to the cyber eye symbols on the sliding doors and his need for Clara to show some attitude and scepticism.
Something really cool was the x-ray water where only organic matter can be seen in the water which is why we could only see the skeletons and not the outer metal shell of the cybermen.
I have so many questions; why has Missy decided to team up with the cybermen? How did she escape from Gallifrey? Why did she regenerate?
In addition, I have a theory- after all the defeats and the victories against the master, why has Missy decided to come back and try to conquer Earth? Is it because once the Earth is gone she thinks that the doctor will stay with her? Does she have some kind of bond or feelings towards the doctor that maybe she wants to try and acknowledge? She has had so many opportunities to kill him and has always decided against it? Why? I need to know!