Silent Witness season 28 ending explained: Is Cal a killer?

Silent Witness season 28 episode 10, the final episode of the series, sees Nikki (Emilia Fox) acting strangely around Jack, while they have a difficult case to crack.

The episode opens with the question of who shot Nicholson remaining. Calvin is with his friend looking out over the Thames. Peggy, Calvin's ex, opens the door to a pile of flowers. Kit is chasing down Nicholson's military record. Nikki tells grumpy Ivor that Nicholson was likely the shooter at the restaurant but they can't be certain. Nikki says they are sure he didn’t take his own life. Peggy calls the police about the flowers, which she says are from Cal, but they aren't being helpful and she sobs.

Maggie asks Nikki if she's got her wedding dress and she says not yet. "You better get a move on!" says Maggie. Nikki seems worried about the wedding. They also discuss that Nicholson has a brain injury. Nikki and Jack go and meet DS Davies at the scene where Akram was murdered. They learn he was killed in the car. DS Davies says the area is known for drugs and erm, dogging! She starts explaining dogging to Jack, who stops her, while Nikki gives a little smile. DS Davies says it’s her first unlawful killing.

The killer used fishing line

A cop goes to Peggy’s house. Meanwhile, Nikki and Jack inspect Akram's body. Jack finds some drugs. "I'm guessing no dogs were involved," quips Nikki. The cop tells Peggy there's no evidence Cal delivered the flowers and therefore they can't do anything. Nikki suggests Akram was killed from behind and the violence involved suggests a personal motive.

Nikki and Harriet go and consult an expert about Nicholson's injuries. She says that people with this type of injury report hearing voices, headaches, memory loss and hallucinations. She says some of the people go on to be violent. Peggy sees on the news that Akram is dead. She's shocked. Nikki performs the autopsy on Akram. Jack thinks the killer used fishing line. We know Cal likes to fish.

DS Davies has a couple of witnesses, who apparently might be doggers! They don’t want to give their real names. They give a little too much info about what they were up to. They mention seeing a delivery van leaving as they arrive. The woman says it was dark blue and had writing on it.

'I'll only do it if Harriet is in charge'

Cal, with his mate, returns to his van — which is dark blue — to find thieves robbing it of packages. One of the thieves runs off, the other pulls a knife and Cal's mate says "he's got this". Nikki is at the home office and they make clear they want Harriet to retire and her to take over. Nikki says they’re a very good team and she won’t do that. "I’ll only do it if Harriet is in charge," she says.

Nikki and Harriet go wedding dress shopping. Nikki tries on a dress and being Nikki starts talking about garrotting! "Can we have some more cakes please?" asks Harriet, enjoying herself. Kit's managed to track down the delivery company from the description they got. But they have 800 vans and no vehicle reg! Jack and Nikki are called to another body. Looks like it might be our thief. They find a crowbar. Has chips of blue paint on it.

DS Davies goes to talk to Peggy about Akram. She says he made her redundant last week. She says he did that because she wouldn't sleep with him. She says she didn’t tell her husband but she says her husband has become a different person in recent times and she has a restraining order against him. DS Davies is very interested when Peggy says Calvin is a delivery driver. Cal gets a message on his phone. Nikki looks at the latest body.

Jack and Nikki recreate what might have happened. Jack shows how the attacker struck the victim in the shin and that the victim must have been raised off the ground. The victim, they believe, then fell, before the attacker slit his throat.
Kit’s tracked Cal’s van, showing he was at various relevant sites to the case including where Akram was murdered.

Cal and his mates are outside the school. One of the mums can be heard complaining that Cal's daughter is a bully. They argue over which of the kids is a bully. "Can you imagine being married to that," says the mum to her mates.

Cal takes hostages

The team learn that Cal was in the army. The annoying mum collects her daughter early from her detention, the teacher isn’t happy. Cal is at the school. He throws the teacher out of the classroom and locks himself in with the mum and the two children. Cal is a man on the edge. The team look at camera footage of what happened in the food store. Cal is joined by his mates in the classroom. But then we see they're not real! He’s talking to himself. Looking at the shop camera footage, you can see Cal is actually by himself. Peggy turns up at the school and starts running when she sees a police car outside. We see delivery van footage of Cal murdering the thief.

The team races to the primary school. Peggy somehow manages to evade the police and gets to the classroom. Cal picks up a pair of scissors, his daughter looks terrified. His imaginary mates egg him on as he gets closer and closer to the mum. His daughter starts speaking and it seems to get through to him. He lets Peggy into the classroom. He lets the mum and child out. Armed police enter the school. Peggy manages to get Dawn out. It's just her and Cal. He wants her to kill him. Cal says he hears things and does things — we see him shooting Nicholson in a flashback. He says Nicholson had the same problems he does and he helped him find peace. "End it" he begs holding out the scissors. He sees the red dots on his body from the police guns. He holds up the scissors in an attacking way, knowing the police will shoot him dead. Later, Nikki looks at Cal's body and finds evidence of his brain injury.

Nikki and Jack are in bed. "Jack, I want to marry you. I was just thinking…". Nikki continues: "We don't have to do the big wedding. I don't need the crowd, the bridesmaids, the big fuss, I just need you." Jack replies: "I just wanted it to be perfect for you." "Marrying you, how can that be anything less than perfect," replies Nikki. Jack says: "So why are we waiting, let’s get married." At the Lyell, Nikki asks Kit to be a witness. Jack asks Harriet to be his best man.

Silent Witness season 28 ending explained: Nikki and Jack get married!

Jack and Nikki are at the registry office. And while Jack’s keen to get things moving, Nikki starts making a big speech. "I've had the hearts of so many people in my hands. As a scientist, I know every detail of the human heart and yet for so long my own has been a mystery to me. Isn't that a wonder?" She ends by saying: "I'm giving my heart to you". Jack replies: "And I'm giving mine to you and I promise to cherish it." Nikki: "I promise to keep yours safe". Jack: "Shall we walk in together." Nikki: "Always".

After the ceremony, we see Harriet and Kit throw confetti over the happy couple. Kit and Harriet both get an email about the Center of Excellence in Birmingham. "What are we going to do?" ponders Harriet.

Nikki and Jack stroll around Trafalgar Square on their wedding night and they dance to "Wings" by Birdy. The pair kiss, Jack takes his jacket off and places it on Nikki. Bless!