Manhattan, with an east wind driving rain mixed with a little sleet along Park Avenue, was as bleak and uninviting as most great cities after midnight, especially in March. There was little traffic – the occasional limousine, the odd cab – hardly surprising at that time of the morning and with such uninviting weather.

In a stretch of mixed offices and residences, a woman waited in an archway, standing in the shadows, a wide-brimmed rain hat on her head and wearing a trenchcoat, the collar turned up. An umbrella was looped to her left wrist. She carried no purse or shoulder bag.

She felt for the gun in the right-hand pocket of her trench-coat, took it out and checked it expertly by feel. It was an unusual weapon, a Colt. 25 semiautomatic, eight shot, relatively small but deadly, especially with the silencer on the end. Some people might have thought it a woman's gun, but not when used with hollow-point cartridges. She replaced it in her pocket and looked out.

Slightly to her right on the other side of Park Avenue was a splendid townhouse. It was owned by Senator Michael Cohan, who was attending a fund-raiser at the Pierre, a function due to finish at midnight, which was why she waited here in the shadows with the intention, all things being equal, of leaving him dead on the pavement.

She heard the sound of voices, a drunken shout, and two young men came round the corner on the other side and started along the sidewalk. They were dressed in identical woollen hats, reefer coats and jeans, and they were drinking from cans. One of them, tall and bearded, stepped into the flooded gutter and kicked water, grinning, but as the rain increased, the other one wrapped his jacket tighter. Spotting the entrance to a covered alley, he swallowed the rest of his beer and dropped the can into the gutter.