The third time out for MacKenzie's retired policeman John Raven who's asked by his sister to investigate the disappearance/death of her au pair girl. She'd been left with her lover's wherewithal--a suitcase of gelignite. The Raven quickly matches this up with a Glasgow safecracker called the Ratcatcher, planning a hit on a London bank. The Raven's just like any crow flying the shortest distance between two points--from known beginning to expected end. The usual.