Harry fixes him with the patient, vaguely pitying look of a man hearing the case doesn't need to be cracked in the same vein as food and water are optional. Some things are survivable, but not without good cause.

"That's why I'll test it," he volunteers. Bravely. "Sixty seconds, in and out. You can time me. You can stand watch, to make clear this is an official investigation. No funny business."

A voice in his head rears up in support of funny business, but Harry dutifully ignores it. He is being a good detective.