I fell apart after that. No one could understand how painful it was for me. No one. They had absolutely no idea about the sharp teeth of guilt tearing at my insides, or the inescapable sorrow that wound itself around my heart like a thickly muscled anaconda tightening its hold every time I exhaled.

I had not been there for him.

My dreams became footsteps that kept taking me back to his killing ground. In my dreams I stood at his window, pale, limp, my hair waving like seaweed in water, and watched him push the needle into his arm. I was the witness. I was there to see the stair I had missed in the darkness.

I woke up in a trembling fury. Rage at everyone. No one was immune from it. Especially me. I sprang to the floor and like a caged animal paced my bedroom restlessly for hours at a time.

That last sniff of him—his perfume after the cells of his body had stopped replicating and replacing themselves—the bouquet of raw meat became a friend. Calling. Calling. Dangerously seductive. My existence had become hellish. I wanted to escape. That day on the boat I had seen Luke become the ocean, the rain, the wind and the blue sky. I wanted all of that and Luke within me, too.

The otherworld… I nearly went.

After one failed attempt, while my mother looked at me with shocked, reproachful eyes, my despairing father who is a doctor quietly persuaded me to consider a temporary treatment of antidepressants.

‘No one outside this family need ever know,’ he said, the terrible guilt of not being able to save Luke skulking in his eyes.

I took the wretched things he gave me. They did the job. They banished my intolerable grief, but I lived in limbo, speaking only when spoken to, eating when food was put before me. And I think I might have been content to exist in that walking dream, on that cloud of dull edges forever, if not for the visit to the toxicologist.

It gave me a fresh pain. It woke me up.

Mr. Fyfield was small, assiduous, clean-cut, well groomed. He opened my brother’s file as if that was the most important thing he had to do that day and in a funeral director’s voice proceeded to explain some of the details contained within. I listened to his voice drift around the room idly until one sentence sent blood rushing up into my brain, so fast I felt it slam into my head.

Whoa! I opened my mouth and made an odd choking noise.

Both my parents turned to stare at me in surprise.

‘But Luke died of an overdose,’ I blurted out. My voice was unnatural, guttural.

Mr. Fyfield spared me an oddly sterile glance before returning his eyes to my parents. ‘He overdosed because the heroin he consumed was spiked with acetyl fentanyl. Fentanyl is an opiate analgesic with no recognized medical use. It is typically prescribed to cancer patients as a last resort. It is five to fifteen times stronger than heroin and ten to one hundred times stronger than morphine.’

The jargon was difficult to comprehend in my state, but one fact was inescapable. I stared at Mr. Fyfield, wide-eyed and trembling. ‘Knowing it could kill him…they sold it to him,’ I whispered.

He looked at me as if I was either stupid or insanely naïve. ‘I’m afraid so.’

I began to hyperventilate. My parents gathered around me protectively. I gasped that I needed a glass of water, which Mr. Fyfield’s secretary immediately fetched. I drank it down and didn’t say a word after that, but finally I was ready to start living again.

Over the next few days I decided that I would join the war on drugs. I made a promise to Luke’s memory. I would do all I could to stop what had happened to him from happening to others. Anyone I saved would live because of Luke’s memory.

I came off the pills. I did research. A lot of it. There were many agencies that I could have targeted, but I found myself gravitating toward undercover work. The idea of using deception to fight deception was perversely pleasing. But, more important, I thought it would be cool to no longer be Lily Strom, the basket case, but an alter ego. Someone new. I could decide who I wanted to be and build her from ground up.

There were two lines of work available as Test Purchase Officers (TPOs) and Undercover Officers (UCOs). Generally TPOs undertook a lower level of undercover work, usually presenting themselves as prostitutes or drug addicts to lure in the small-time dealers. Their assignments were unglamorous, quick in and out jobs that typically lasted only hours.

UCOs were a totally different kettle of fish. They lived in a different world, one shrouded in secrecy, taking on different names, different addresses and totally different ways of life, sometimes for years at a time. The most elite and secretive of these units was called SO10 or SCD10. So secret most police officers didn’t even know it existed.

Although it was easier to be accepted as a TPO I knew I didn’t want to be a TPO. My heart was set on being a UCO. They brought in the big fish. The kingpins. The ones I wanted to target.

‘You’ll have to finish your education if you want to be accepted in an agency like that,’ my father said.

So I diverted all my rage and energy into work, graduated with honors, and applied to be a police officer. They accepted me and sent me to the Police Academy in Hendon. It was a flat, depressing place that looked exactly like one of those eyesore housing estates from the seventies; only it had a large swimming pool and a running track.

The training was undemanding: for twenty effortless weeks they taught us to unthinkingly and unquestioningly obey the chain of command at all times. But I was strangely glad of the strict parameters of authority that we had to conform to.

I came out of it a police officer.