The Ghost Squad: Firewall

Amy has three targets within the Witness Protection Unit: DC Richard Ellis, DS Tony Sharpe and DS Jimmy Franks. One of them is corrupt and desperate to prevent Brendan, the sole witness to a murder, from giving evidence. Without him, the murderer, Warren Cole, walks free. Amy is assigned to work alongside them, finding herself baby-sitting Brendan in a safe house, giving him constant reassurance that he's safe and doing the right thing.