Recap: After saying goodbye to Beth and her dad at the train station in Exeter, we load our cases on and find our seats.

"Right," John says, pulling out his laptop as we sit down. "Best write this case up then."

"What's it going to be this time?" I smirk. "'The Hounds of Baskerville'?" John's eyes widen and I roll my own. "I wasn't being serious."

"No it's - it's the blog," he says, spinning the laptop around so we can see the screen. The entry at the top, the most recent one, is titled 'Hello Boys!' I click into it and read the short message.

"He's back."

Prologue

A few weeks after the Baskerville case, we have got no further towards finding Moriarty than we were before. For just a few minutes, he came out from hiding but now he's gone back underground and is leaving no signs of what his motive was. No doubt he's building up a network again.

So instead, we're trying to track down another case - one which lasts more than half a day. As always, we're getting nowhere. A couple missing people, a murder suicide and a lost inheritance scam. Hardly anything interesting.

"Really starting to wish the criminal classes would get back to work," I sigh, closing another newspage. "No major case has happened in weeks."

"Has Beth not sent you anything?" John asks and I shake my head. Beth and I had an agreement before we left that she would keep an eye out on a local level to see how things settled after we left. For the sake of tourism, they've tried to keep on as usual.

"Nothing," I reply and walk over to the window. "Hey, this looks promising." Dad comes over to the window and looks out to see what I'm meaning. A blonde woman in a black suit steps out of a cab outside our flat and starts towards the door. Looking her over, she looks shaken but controlled - as if she has seen things go wrong before. Her coming here would suggest something has happened which is beyond her control.

We might just have a case!