As she steps out of the car, the rain assaults her face and hair. She pulls up the collar of her pea coat, which thankfully keeps off the worst of the cold.

The Aylesbury Estate is known as Britain’s finest example of urban decay and after years of residents’ campaigning, the council has put money into regenerating the entire estate. It has been a slow process and some flats still remain unoccupied. Archer crosses the road and makes her way up the concrete stairs to the Kellys’ flat on the fifth floor. The walls are daubed with unimaginative white, yellow and orange graffiti comprising illegible names, profanities and various depictions of genitalia. Despite the evening cold, she can still make out the unmistakable stale stench of urine.

She hears footsteps approaching and stops to look up, but sees only shadows. Archer peers along the fourth-floor walkway but there is no one there. She moves on to the fifth floor and makes her way down the external corridor, hears the whine of a car alarm and wonders if it has been triggered by the storm or an opportunistic thief.

A pleasant and fragrant wave of garlic, cumin and coriander wafts under her nose as she passes a kitchen window, which is open an inch for ventilation. She hears the laughing voices of a happy family and envies them being together in the dry warmth ready to eat a delicious meal. Archer’s mouth waters and her stomach rumbles. When did she last eat?

She approaches Elaine Kelly’s flat at the end of the corridor, stepping from a haze of spice into an invisible curtain of bubble-gum sweetness.

Like spray paint.

Fresh spray paint.

She freezes.

A life-size figure of a semi-naked woman with floating blonde hair, her hands raised in prayer, has been painted on the wall at the end of the corridor. It’s Elaine Kelly looking back at her.

Archer feels her pulse quickening. She notices the door to the flat is ajar, the lock is broken where it has been forced open.

The footsteps on the stairs.

He has been here. Just now. She peers over the wall at the forecourt below, her eyes blinking at the rain. She scans the area but sees no one. Then something catches her eye by the cluster of communal bins. Archer squints and sees a man looking up at her. The hairs on her neck stand on end. The figure turns and hurries out of the estate.

‘Hey!’ cries Archer as she springs forward, sprinting toward the staircase.

An Indian man with a stern face appears. ‘Can I help you?’ he asks, but Archer dodges past him and runs down the steps, her phone pressed to ear, Quinn’s number ringing but he doesn’t answer. She takes the damp staircase two steps at a time, gripping the bannister to avoid a fall and a cracked skull or broken limb.