He smiled and nodded slowly. ‘You miss the rush, don’t you? There’s nothing quite like it.’

She knew he spoke from bountiful experience. Frank had worked in undercover roles on countless operations over the years before eventually taking over the reins. He had an ex-wife and a kid he never saw who were casualties of his relentless dedication to the job. And to that end Bailey knew first-hand what a hard taskmaster he could be.

He was right, though. She did miss the rush of working undercover. It made her feel alive like nothing else, especially when normal life made her feel as if she was dying inside. But the buzz wasn’t the only reason she was here. Not by a long stretch. Alice was the main reason.

‘So what’s the deal?’ she said.

The smiled faded. He cleared his throat.

‘As you may already be aware, drugs in prison are a major social issue and a political hot topic. They’re worth up to four times their street value inside and it’s estimated that the drugs trade in the UK prison system is worth around a hundred million pounds a year.’

‘Big business,’ she murmured.

‘We’ve been aware of the problem at HMP Foxbrook for a while now and this operation forms part of the Government’s overall initiative to clamp down on drug use and drug dealing within the wider prison system.’

‘So just how big is the problem at HMP Foxbrook?’ she asked.

‘Well, we know that drugs get into the prison through all kinds of means. Visitors smuggle stuff in. Corrupt staff smuggle stuff in. Stuff gets chucked over the wall. Stuff gets hidden in packages posted to prisoners. Stuff gets flown in by drone. But that’s all small fry. What we’re concerned about here are much larger quantities. We suspect the existence of an organised drug smuggling and distribution ring who are working at scale.’

‘Where’s the budget for this operation coming from?’

‘The operation is being funded by the Metropolitan Police, more specifically the Basic Command Unit which covers the borough that the prison lies in. Drugs detectives from that BCU will be overseeing the operation and they’re also in charge of the budget. They’re the ones I’ll be reporting back to with any intelligence that you gather.’

The Metropolitan Police was divided up into a number of Basic Command Units, or BCUs, each assigned to a specific geographical area of London.

‘So basically the whole thing’s being run by the local drugs squad,’ said Bailey.

‘That’s more or less correct,’ Frank agreed. ‘They want you to uncover how the drugs are entering the prison and they want to identify the key players involved. Once we’ve nailed the perpetrators, we should be able to find out who on the outside is behind the supply of drugs to the prison. We think that a major organised crime group is responsible. When we reach that point, the NCA will probably want to step in, so they’re very interested in the outcome of this operation.’