The story begins with a young man named Matthew Bedser, an RAF pilot flying in a training exercise over Stonehenge. Everything seems normal right up until his plane flies through a portal and into another universe. When young Bedser returns to his own time and place minutes later, he is horrified to discover something vital missing from his plane: the nuclear missile it had been carrying. Bedser, once landed safely on solid earth again, is taken in for an interview with a top military specialist with experience dealing with unusual happenings.
Tropes present in The Shadows of Avalon include:
- Face–Heel Turn: The Brig doesn't do this completely, but he actively works against the Doctor in favor of a strategic military advantage to Britain throughout most of the novel, leading in the end to a Heel Realization. Also, Romana, who appears to have lost all sense of principal when she sends to sadistic CIA assassins after Compassion and seems like a totally different character.
- A Father to His Men: Who do you think?
- I Choose to Stay: The Brigadier.
- Measuring the Marigolds: The Doctor wants to stop Compassion from seeing the world this way, so he leaves her on Earth for six weeks with a list of things to accomplish to make her "more human". This fails epically.
- Spaceship Girl: Compassion is turned into a TARDIS as a side effect of the Doctor programming her receiver to only pick up signals from the TARDIS.
- What the Hell, Hero?: Stranding Compassion on Earth for six weeks to make her act and think more like a human is kind of a Jerk Ass move from someone who says he values everyone for their uniqueness.