If I said I didn't see this coming, I'd be lying. I knew there was something off about Oliver Bright.

And I knew I was right.

I also knew that Sasha was in danger – that Oliver would go after her and her family. I can't deny that it's part of the reason I went to her house. That will make Jack angry later, but I can't deny it. I put myself in danger again, but as far as I'm concerned, it was the right thing to do.

I wanted to talk to her – to ask her about Oliver, but I could have done it over the phone. I'm not trying to be a hero, this is my job. Sure, I don't often get a live one, but I'm a doctor and I save lives – even when it's just giving somebody dignity in death and their families closure in knowing how they really died. Sometimes in finding out how someone died, I can save others. I'm a doctor. It's what I do. I did the right thing – and I'd do it again.

So, I went to Sasha's house, knowing the murderer was probably on his way there too.

I knew I was walking into the Lion's den.

At Sasha's house...

Sasha is shocked by my suggestion.

"What, you think Oliver did this? That doesn't make any sense."

Maybe not, but I'm so sure. "Could Oliver have hidden his true reasons for killing Charles Moore?"

Sasha doesn't look convinced. "He would have had to mask all his symptoms from the start. The psychometrics, assessments, all my work with him..."

I know I'm right though. I've worked it all out. It can only be Oliver Bright, so I push the matter. "But is it possible?"

Sasha doesn't answer straight away. She considers the possibility. "His rehabilitation wouldn't have been addressing the reasons he killed." She answers eventually. She fears I'm right about Oliver.

"So he wouldn't have been getting any better, but he could have been getting worse."

I'm interrupted by the doorbell and we hear the police guard open the door – but then there's a thud. Sasha pushes me towards the sofa where her mum and Max are sitting and goes out into the hall. For a while, there's just silence, but then we hear Oliver Bright.

"Who else is here?"

Sasha backs into the living room, Oliver is pursuing her.

"My mum, my little boy, Dr Alexander..." She whispers. "It's ok. She just came to see how I was, she's a friend." Sasha adds hurriedly, seeing Oliver give me a menacing look. There's no need to ask what happened to the police guard. Oliver is covered in blood and there's a knife in his hand.

I think we could be next.