“You’re defining ‘best’ and ‘worst’ by how exciting you think the investigation is going to be, are you?”

“Yes I am,” Anik replied defiantly, opening his eyes and lifting his head. “It’s better than arresting a 70-year-old man with a bag of wee strapped to his leg, anyhow.”

Then he gagged a little as Laura changed lanes too quickly. She pulled into Sainsbury’s petrol station, so they could swap places.

Ridley glanced in his rear-view mirror and watched Laura pull off the M1. At the same time, Jack’s mobile pinged. Message from Laura:

Anik needs to puke. L x.

“Toilet break,” Jack lied to Ridley. “Laura knows where she’s going, so they’ll catch us up.”

Jack continued to flick through the file on his knee.

“We’ve got statements from hundreds of people from back in ’95. DI Prescott’s highlighted the ones we need to focus on.” He read out loud in bullet points for speed: “Former mounted officer Norma Walker—last rental occupant of Rose Cottage. Dorothy Rawlins, also known as Dolly—last owner of nearby manor house, The Grange. She and five other occupants all interviewed. John Maynard—builder working at The Grange in ’95. James Douglas—railway signalman on duty on the night of the train robbery.”

Ridley allowed Jack to finish his list before speaking.

“Check Dolly Rawlins.”

Jack logged into the HOLMES app. A moment later, he glanced at Ridley in astonishment. Ridley was looking smug.

“Dolly Rawlins,” Jack read out loud. “Convicted of the murder of her husband, Harold Rawlins, also known as Harry. Shot to death on August 27, 1995, by Ester Freeman. She sounds like she could have known an armed robber or two.”

“Who was in charge of the investigation back then?” Ridley asked.

“Newman. Deceased. But we’ve got access to a retired mounted officer called Bill Thorn. He knew Norma Walker personally and was on the front line of Newman’s investigation.” Jack closed the file. “So, back in the day, this gang got away with £27 million pounds. They burn one point eight million in old fivers and tenners ’cos they can’t spend it legally anymore, leaving them with twenty-five-ish million in legal tender. And whatever they plan to do, they’ve got to do it fast—because next year, the new twenty’s due to come into circulation.”

For the first time in ages, Jack felt his heart beat a little faster at the prospect of a new case. He thought back to poor old man Sweeney gripping his arm as he shuffled toward the police car with his trouser leg pulled up and a catheter bag in his hand. This felt different. He thought of how he’d said to Maggie that he wanted to feel excited by his job, just like she does, and here he was . . .

Ridley noted Jack’s wide eyes, raised eyebrows and relaxed posture and congratulated himself. This was the look of an officer who was alert and ready to investigate. He’d been right about Jack, after all.

“What are you doing about the sergeant’s exam?” Ridley’s question snapped Jack out of his daydream.