Natalie. Charlie had a name at last – only a first name, but still, it felt like a big step forward. She celebrated with a sip of ginger beer from the can on her desk. It was warm and flat, leftover from yesterday, but she was in too good a mood to care. Ginger was a taste that nothing could destroy, especially when you’d just found a short, grainy film on the web of Nikhil Gulati giving a best man’s speech and, in it, referring to his girlfriend as Natalie.

The film was on the YouTube channel of Philip Sier, the groom. Nikhil’s speech had made Charlie laugh twice. It was witty without being attention-seeking; it kept the spotlight firmly on Philip and Emily, whose special day it was. Best of all, it referred to ‘my better half, Natalie’, who was also present and whose embarrassed face helpfully filled the screen at the exact moment her name was mentioned.

Charlie opened the Liv and Gibbs file on her computer and added the new information – ‘Nikhil Gulati’s girlfriend’s name: Natalie’ – to what she already had. She’d found out quite a bit about Nikhil. No criminal convictions, no history with the police – that was the first thing she’d checked. He wasn’t on Facebook, but she’d found him on Twitter and LinkedIn. He was Associate Marketing Manager for the R & T McElwee Winery in Linton, Cambridgeshire. Before taking that job in 2011, he’d had a similar role at Gallo wines in Uxbridge. His Twitter feed revealed him to be the doting owner of two pugs – Doug the Pug and Peppa Pug – as well as a member of the Liberal Democrat party and addicted to spicy foods, the hotter the better.

Nikhil had joined Twitter in 2012. There were several references among his tweets to ‘Her Outdoors’, which had led Charlie to speculate that the girlfriend had a non-office-based career. Her Outdoors wasn’t addicted to Twitter as he was, Nikhil told one of his followers on 11 April 2013; she thought he was crazy to waste so much of his time on it. Charlie, by contrast, was glad he had, because it was his Twitter activity that had led her to Philip Sier, Nikhil’s best friend since university.

And now, thanks to Sier’s YouTube channel, she’d been able to add the name Natalie to her notes. Everything was shaping up nicely.

Charlie felt like doing something to celebrate. She had a sudden urge to be on the move. One minute it presented itself as excitement, the next as anxiety. Everyone was capable of doing something life-ruiningly stupid, but Charlie believed her sister to be more capable of it than most, and they were too close, their lives too intertwined, for Charlie to maintain a safe emotional distance. Not caring – taking no further action – wasn’t an option.

The only way to kill the fear was to find out the truth.