Doctor Who and an Unearthly Child by Terrance Dicks
As boldly announced on the cover, this book is the "First publication of the very first Doctor Who story." Having never seen the very first episode, I was intrigued to read the book. The story has many elements that have lasted throughout the years--kidnapping of the Doctor and his friends, escaping and being re-kidnapped, co-ordinating various skills in the group, discussing the "it's bigger on the inside" nature of the TARDIS, and traveling to an exotic time.
The story starts with Susan, a brilliant school student who doesn't know some of the basics, like how pre-metric English money works. Two teachers, Barbara and Ian, are concerned about her and follow her home to the address the school has--a junkyard in town. In the yard, they don't see Susan but they do see a perfectly serviceable police box and an old man fussing around. Soon enough, they are inside the TARDIS and wind up in pre-historic Earth where a tribe of cavemen fret over the invention of fire. Action and excitement ensue.
I enjoyed the story though the writing is very plain. It's the perfect sort of beach-reading fun novel. The Doctor Who connection is a bonus. Now I must hunt down the original episode on DVD or streaming somewhere.