John stepped up and shone his torch onto the back of Sally's head, moving its beam down the back of her jacket.
"Looks like water." He peered closely . "Yeah, definitely just water."
"Interesting." Sherlock said, joining him and stroking his fingers through Sally's hair then rubbing his fingers together meditatively.
"Oi Freak! Leave my hair aloneā¦." Sally screeched, her voice echoing down the tunnels.
Lestrade sucked in his cheeks to prevent a smile breaking through. From behind the sergeant John threw him a grin.
"I was merely checking John's findings," Sherlock lifted his fingers and sniffed. "Not clean water though, it has the smell of petrol and diesel."
"How?"
"Rainwater run-off, this has washed off the roads and down the drains."
Turning his attention back to the walls and ceiling of the tunnel Sherlock moved nimbly back down towards the body and beyond, his head swivelling as if unconnected from his neck.
Ten yards or so past the corpse he stopped and looked up, backed up a pace and held out his hand. Watched by three pairs of eyes he finally sniffed his fingers once more.
"What have you found?" Lestrade asked as the slender man hurried past him, back to where Sally had been standing and looked up once more.
"Lestrade," he said, "I believe we've made a breakthrough!"
