The Seventh Doctor, Ace and Hex are found unconscious on a World War I battlefield in France (in what would become a continuing feature in the Doctor's life). They end up at a military hospital. By a stroke of tremendous luck, a letter arrives from high-up telling the commanding officers that team TARDIS is a ragtag bunch of military detectives. Their job: to investigate a murder that will be committed later that day.
The hospital, full of wounded soldiers, does things not quite by the book. For one, there's a place called the "hate room", where soldiers can work on their aggression skills and patriotism. The group soon befriends a young soldier named Taylor, who spends much of his time type-writing letters home to his girlfriend. (His handwriting is atrocious). Hex, who's trying to keep a cool head, offends a local character named Wood with how uncomfortable he is around soldiers. Hex' first instinct is to tend to the wounded and to speak up about how horrifying and inhumane war is. Wood, who doesn't have the slightest patience for "cowardice", drags Hex into the hate room, unceremoniously ties him to a chair, clamps down his tongue and starts giving him a few hours of Electric Torture. By the time the Doctor finds his companion, Hex has been drugged with Easy Amnesia and wonders what on earth happened to him.
The Doctor soon realises that the letter about him was subconsciously written by Taylor, who's also going around stabbing and shooting people in his sleep. It's obvious to team TARDIS that the hospital is manipulating the wounded soldiers using rudimentary Freudian theory. The brainwashed soldiers are made into traumatised shells of men who'd do anything for their country. Also, Taylor tells Ace that he was wounded at a terrible battle against some German soldiers — and, as he waited for help to arrive, surrounded by corpses, he saw an angel.
While Ace and Hex go off to investigate the site of the battle, Wood (the Doctor's primary subject) is murdered. His higher-up, Brook, instantly blames the Doctor and organises a firing squad out of the traumatised soldiers for a very quick execution. The Doctor escapes on a motorbike, joins up with Ace and Hex, and realises that Brook's experiment went further than anyone had suspected: there were never any German soldiers to begin with, and the entire massacre was just British soldiers brainwashed into killing each other. Taylor now has to live with having killed Wood while sleepwalking, and Hex begs to be taken back to the TARDIS, or any place where there isn't a war going on. The Doctor tells him that death is always a tragedy, but he shouldn't see it as a waste of life... because life is never wasted as long as it was lived honestly. All's well that ends well, except the Doctor very glumly reveals that the entire thing was engineered by... the Forge.
- Angry Guard Dog:"I didn't know they had guard dogs!"
- Asshole Victim: Wood and later, Brooke.
- Brainwashing for the Greater Good
- The Bus Came Back: The Forge is back after years of absence.
- Call-Back: Hex remembers Ireland very bitterly, and has a brief conversation with Ace about his mom, Cassie.
- The Doctor and Taylor discuss the classic philosophical problem of killing one innocent child to save thousands. Seven's moral inability to do just that has long been a particularly morbid Running Gag in Big Finish.
- Ace mentions not having seen angels... Well not like the ones Captain Dudgeon has seen.
- The Chew Toy: By this time, the writers were joking amongst themselves who could torture poor Hex the hardest.
- Cold-Blooded Torture
- Deadly Gas
- Don't Call Me "Sir": Sergeant Wood has issues with the higher ups, who don't know about the hardships the Tommies in the fields go through.
- Foreshadowing: Plenty of it for Hex' final episodes.
- Gone Horriblyright
- Hoist by His Own Petard: See the second entry for Asshole Victim.
- I Am Not a Gun
- I Did What I Had to Do
- Jumping Off the Slippery Slope: Hex muses that if there's brainwashing in WW I, how does it stop people from being alike to the Cybermen?
- Maybe Magic, Maybe Mundane
- Never Wake Up a Sleepwalker: Subverted.
- Officer and a Gentleman: The Lieutenant-Colonel Brook and Captain Dudgeon are very polite. [It's an act for Lieutenant-Brook.
- Ominous Message from the Future
- The Reveal: The final lines of the episode reveal that the entire experiment was done by the Forge.
- Secret Test of Character: Brooke replaced all the soldiers' rifles with blanks for the Public Execution.
- Science Marches On: The Doctor says all of his "six senses" are in working order. Though commonly believed that humans only have five (touch, taste, sight, hearing and smell) they have at least two more: equilibrium and of time (passing).
- Shell-Shocked Veteran: Captain Dudgeon had a near death experience, and the sole survivor of a platoon.
- Sherlock Scan: Hex manages to deduce they are on Earth, before his time, by the wallpaper. This is Handwaved by him saying he "knows wallpaper".
- Shout-Out: The Doctor mentions Groundog Day.
- The Man Behind the Man: The Forge.
- Title Drop
- Vitriolic Best Buds: Ace keeps trying to invoke the trope with Hex, constantly teasing him and making lame jokes about gender stereotypes. Hex really isn't in the mood, and just wants to get out of the war.