Jack Knife

This debut novel features an intriguing setup that, unfortunately, becomes bogged down in a too-busy narrative: American time travelers from the year 2007 find themselves in 1888 London on the trail of a dangerous interloper from their time, just as the escalation of the legendary Jack the Ripper murders has driven the city into a frenzy. Wary that they or their quarry, Jonathan Avery, might change history in a way that would eliminate their own time line, partners-of-convenience Sara Grant and David Elliot simultaneously search for their target while attempting to assist Scotland Yard Insp. Jonas Robb in thwarting the sadistic serial killer—who may be one and the same. What they don't realize is that Avery has taken a much larger role in events, and that it may be too late to salvage their future. A keen sense of history (such as the inclusion of lesser-known Ripper suspects Francis Tumblety and Michael Ostrog) bolsters this fast-paced pale, but Baker piles on bite-sized scenes and jarring shifts among characters to overwhelming, disorienting effect. (Feb.)