There's a man across the road called Shaz. His full name is Shazad but we've been told to call him Shaz because that's what everyone does. And he happens to be one of the few people on our road to have invested in CCTV footage. And as an upstanding citizen of the great city of Birmingham, he's obliged to the police's request of the footage from the camera facing our house.

"I was home," I tell Diane when we're sat down in the living room. "I came home from the station where I talked to you with my mom and I didn't leave again."

"No you did," Dave contradicts. "You took the rubbish out, remember? And put the bins out?"

"Oh yeah. But that's just the front garden, it doesn't really matter does it?"

"Front garden's fine," Diane assures him. "So you didn't travel to Dugray Grammar School to partake in the death of Mr Granger?"

"No," I say. "I didn't do anything. Why would I kill Mr Granger?"

"Why would Eden Davis kill Josh Hartley?" Diane's partner, Mitch, asks. "Because you told her to."

"So she did confess." When they look at me strangely, I explain. "She texted me last night telling me she was going to confess."

"And maybe that was the motivation to finally kill Granger. She goes down, you go down? Like, you go down together?" Mitch suggests.

I snort. "That was a joke. I would never kill someone, especially my History teacher. And how would I do it? Bury him under my GCSE revision guides?"

I admit, I'm getting frustrated with all the questions. They have the camera footage, they can watch that and see that I didn't leave the house after I returned with Mom. They can contact the school and get the footage from there to check that I didn't step foot on the premises after I left on Tuesday. They can even go to Granger's street, find that street's Shaz and make sure I didn't go near his house either. I don't know where he lives, but they can do that to bring themselves comfort.

"Is that it?" Dave asks.

"Just one more thing," Mitch says.

I don't like Mitch. Mitch isn't calm like Diane, his cold eyes are calculating which might mean that's he's crazy clever, but all it feels like to me is that he's X-raying my soul to see if I'm lying or not.

"Were you aware of why Eden brought up Granger in your, um, conversation?" he asks.

"No," I say. "She said something cryptic, like she had her reasons or something. She never told me why specifically."

"So you didn't know about Eden's older sister Erin? That she gave birth on Sunday?"

I freeze. "What, to a baby?"

"Eden became aware of your teacher's affair with her older sister and his refusal for any support during the pregnancy. That's why she wanted him out." Mitch's words are cold.

I didn't even know Eden had an older sister. No, wait I did. She wasn't anyone too noticeable, probably a few years above us in primary. The girl who came to collect Eden, out of breath like she just ran from the secondary to our primary in her purple tie and black blazer.

"I didn't know that," I whisper. "But what does that have to do with me?"

"That's what we need to find out. Eden killed Josh because of that conversation with you. You were supposed to kill Mr Granger in return. But you didn't and he ended up dead anyway. So what on Earth happened?"