The next morning, Beth meets us outside the Cross Keys for breakfast.

"You okay?" I ask her as she sits opposite me, waiting for our meals to come.

"I think so," she sighs. "I've seen a lot this week - some of which I wish I hadn't. But I've had the best time of my life, honestly."

"Put you off for life?" I grin and she laughs.

"Not quite!"

Billy brings out a plate of vegetarian breakfast and puts it in front of John.

"Mmm," John says, looking down at the plate. "Thanks, Billy."

As Billy walks away, dad brings over our drinks and sets them down in front of us.

"Ta," I say, bringing mine closer to me. "No suspected narcotics in this one then?"

"No," dad shakes his head. "You're safe." I grin and blow gently on the surface so it can cool down quicker.

"So they didn't have it put down, then – the dog." I say as John starts tucking into his breakfast.

"Obviously," he answers. "Suppose they just couldn't bring themselves to do it."

"I see."

"No you don't," John smiles.

"No, I don't," I admit. "Sentiment?"

"Sentiment!" John confirms and I roll my eyes.

"Oh."

"Listen," John says as dad sits down beside him. "What happened to me in the lab?" Dad looks uncomfortable before reaching to the condiments caddy in the centre of the table as he tries to work out how to explain himself.

"D'you want some sauce with that?"

"I mean," John continues, ignoring him, "I hadn't been to the Hollow, so how come I heard those things in there? Fear and stimulus, you said."

"You must have been dosed with it elsewhere, when you went to the lab, maybe," dad suggests, not making eye contact. I exchange a knowing look with Beth who smirks. "You saw those pipes – pretty ancient, leaky as a sieve; and they were carrying the gas, so ... Um, ketchup, was it, or brown ...?"

"Hang on," John says in realisation, "you thought it was in the sugar." Dad raises his eyes and stares at him while trying to maintain a neutral expression. "You were convinced it was in the sugar." Dad looks away again.

"Better get going, actually," he says, looking at his watch. "There's a train that leaves in half an hour, so if you want ..."

"You're joking right?" Beth laughs. "You'd never get up to Exeter in half an hour!" I laugh with her as John turns his head away in realisation.

"Oh God," he says. "It was you. You locked me in that bloody lab."

"I had to," dad replies defensively. "It was an experiment."

"An experiment?!" John repeats furiously. Dad looks around at the people sitting nearby and shushes him. "I was terrified, Sherlock," John continues, quieter but still furious. "I was scared to death."

"I thought that the drug was in the sugar, so I put the sugar in your coffee, then I arranged everything with Major Barrymore." John sighs in exasperation. "It was all totally scientific, laboratory conditions – well, literally. Well, I knew what effect it had had on a superior mind, so I needed to try it on an average one." John looks up from his plate and dad rolls his eyes. "You know what I mean."

"But it wasn't in the sugar," John establishes as he returns to his breakfast.

"No," dad says, then quickly tries to defend himself, "well, I wasn't to know you'd already been exposed to the gas."

"So you got it wrong," John pushes and I grin.

"No.

"Mmm," I join in. "You were wrong. It wasn't in the sugar. You got it wrong."

"A bit," he admits finally. "It won't happen again."

"Any long-term effects?" John sighs.

"None at all," dad says. "You'll be fine once you've excreted it. We all will."

"Think I might have taken care of that already," John says and I snort with laughter. Dad looks over to where Gary is pouring coffee for two other customers. He looks up and smiles apologetically across. Dad stands up and puts his mug on the table.

"Where're you going?" John asks.

"Won't be a minute," dad replies. "Gotta see a man about a dog."