Most of the regular cast of a Spenser novel appear in Sudden Mischief: Spenser, Susan Silverman, Hawk, and Martin Quirk; Henry Cimoli makes a cameo appearance.

Rita Fiore, who played a lead role in the novel Small Vices, as a successful practicing attorney who is disenchanted with the legal system, also reappears. She gives Spenser some crucial advice about Francis Ronan.

Rachel Wallace, a feisty, sharp-tongued lesbian activist whom Spenser once protected, also reappears and provides caustic social comment and an amused assessment of Spenser and Susan's relationship.

All of the series's regulars play minor roles in Sudden Mischief. Hawk is limited to a background role as an assistant in Spenser's investigation of Brad's past, although his repartee and sardonic social commentary add humor and perspective to the novel.

Much of the novel's focus is on the relationship between Spenser and Susan and on the possibility that it...