The upper landing outside Ed’s bedroom was silent, and illuminated only by a low-voltage bracket lamp. Della paused for a moment, and looked carefully along the landing towards the double doors of Shearson’s personal bedroom suite. They were closed, as usual, and probably locked. One of the Muldoon brothers had told Ed that Shearson had once been attacked in a hotel in New York by a prowler, and ever since then he had been neurotic about the idea of being surprised in his sleep.

‘Don’t they have anybody patrolling the house during the night?’ whispered Ed.

Della shook her head. ‘The Muldoons check on all the doors and windows before they go to bed, and switch on an outside alarm; and there are a couple of Dobermanns loose in the grounds. For tonight, they’ve closed down the switchboard, too. The only telephone that works is Shearson’s private line. Maybe Peter has a phone, too. But that’s all. They don’t need much else in the way of security, out here in the wilds.’

She gripped Ed’s sleeve, and led him swiftly along the length of the landing to the angled cedarwood staircase. The stairs were so well constructed that not one of them creaked as they padded down to the main living area. They waited for just a second, listening, to make sure that they hadn’t been heard; and then they crossed the wide living-room floor, and approached the passage to Shearson’s study.

A portrait of a sour-faced trooper by George Caleb Bingham observed them from the passage wall; and a little further along, they were stared at fiercely by a Kwakiutl Indian mask in green and scarlet, fringed with real human hair. The cold magnetic light of the moon fell across the passage from a triangular wood-framed window, and pointed to the door of Shearson’s study as if it were a mystic sign.

Della said, ‘Keep an eye open, will you? This shouldn’t take long.’ And while Ed loitered at the corner of the passage, wishing that he’d thought of going to the bathroom before he ventured out on this bag job with Della, she reached into the pocket of her emerald green bathrobe and took out a plastic envelope, which, by the clinking sound it made, probably contained lock-picks.

‘They teach you to burglarise people’s houses?’ asked Ed, in a breathy whisper.

Della raised one finger to her lips. ‘They call it “gaining essential access”. It’s only called “burglarisation” when you get caught, and the agency disowns you.’

She peered at the lock closely. ‘It’s nothing special,’ she told him. ‘A five-lever armour-plated deadlock.’

‘Is that all?’ asked Ed. ‘In that case, you should be able to open it with your hairgrip.’

‘Will you keep a look-out, and shut up, and trust me?’ hissed Della.

Ed waved a hand at her to calm her down. ‘Just open the door. I trust you.’