Ace

Dorothy Gale "Ace" McShane, was a companion of the Seventh Doctor. She was a human from late 20th century Earth. She was a troubled teen on Earth, expelled from school for blowing up the art room as a "creative statement". Gifted in chemistry, she was in her room experimenting with the extraction of nitroglycerin from gelignite when a time storm swept her up and transported her to the deck of Sabalom Glitz's spacecraft, which was docked at Iceworld far in her future. Trapped on Iceworld, she got a job as a waitress and some time later met the Seventh Doctor and his companion Mel. When Mel left the Doctor at the conclusion of their battle with Kane, he offered to take Ace with him in the TARDIS, and she gladly accepted.

Under the Doctor's tutelage, Ace fought the Daleks and faced Davros. She opposed Helen A and her sadistic government, which required people to be happy on pain of death. She stopped the Cybermen from getting hold of Nemesis in 1988 and saved the Psychic Circus on Segonax from the Gods of Ragnarok. She also met Brigadier Lethbridge-Stewart, helping UNIT defeat the Destroyer and Morgaine.

The Doctor forced Ace to face demons from her past, taking her to a house she burned down a century before she did. There she discovered that the presence in the house of the Entity known as Light was what she had felt when compelled to burn the house down.

Ace called the Doctor "Professor". She was convinced he needed his back watched and protected him with a fierce loyalty. In turn, the Doctor took a special interest in Ace's education, taking her across the universe and prompting her to figure out explanations rather than giving her all the answers.

I quite like Ace generally but in this story I loved her. I thought she was excellent and Saber summed everything up brilliantly.

Ace is one of my favourite companions, along with Leela, and she doesn't get much better than this.  I agree with Saber - you can see the effects of the therapeutic experiences she's been through in Ghost Light & The Curse of Fenric - not to mention the story I wrote between TCOF and this

This is my favourite Ace story so far. Not seen many, but this one has been the best. She just seemed so much better here.

And this!

In fact, I was surprised by just how much I liked her in this. It makes me excited to check out the rest of S26.

I agree with most of what has already been said. Ace wasn't a favourite of mine but she worked really well alongside Seven and Sophie Aldred put in a great performance here.