But there is something strangely plausible in Lucan seeking her out even though he knows her to be a bogus (albeit successful) psychiatrist. They have a good deal in common.Both figures are fugitives from the law. They have both been on the run and have escaped justice due to the misplaced loyalty of "aiders and abetters". Both have also been forced to assume alternative identities (Spark's Lucan undergoes plastic surgery). Beate Pappenheim's blood ritual, in particular, is dramatically related to Lucan's murder victim, Sandra Rivett, whose blood "got everywhere Pools of it". Beate, the holy stigmatic, who is also based on an actual person, imitated one of the five wounds of Christ by covering herself in menstrual blood.Spark's fiction invariably teases out the differences between superficially similar figures of good and evil.

Hildegard and Lucan are both in the "blood business" together. Not unlike the ideal novelist, the "Wolf method" of therapy combines a God-like authority with Hildegard's distinctive voice (she speaks continuously to her patients for the first three sessions). Lucan, in contrast, is a bad writer in aesthetic and moral terms, who believes that it is his "destiny" to kill his wife. His murderous plot "leaked" like a "blood-oozing mailbag".What stops Aiding and Abetting from becoming overly moralistic is the exuberance of its story-line - which encompasses Central Africa and the Scottish Highlands as well as London and Paris - along with an engaging playfulness. The "facts of blood" are not reduced to mere biology but given a gloriously expansive set of meanings.

As Hildegard's lover says of her past spoof activities: "What else should a woman of imagination do with her menstrual blood?". While Hildegard's imagination is able to transform her circumstances, Lucan, utterly devoid of imagination, fails to abolish the "blood" and "mess" which he had unleashed in 1974.Spark's ability to see everything with double eyes leads, at its best, to a generosity of spirit and ingrained pluralism. For this reason, Hildegard's fear of the past is countered by the everyday pleasures of making art. In an extraordinary ending, set in a fictitious country in Central Africa, everything in Aiding and Abetting is turned on its head. Until this point, Spark had set up the fundamental distinction between blood as mere matter (Lucan's daily diet of lamb chops) and the transfiguration of the blood of Christ.But when looked at from an African perspective, this return to Catholic first principles is given a completely different tenor. That Spark has managed to create such an astonishingly ambitious work in her eighties shows, more than anything else, the enduring power of her artistic gifts.