The fifth in the crime fiction series featuring bulldozing DS Washington Poe of the National Crime Authority and his odd-couple partner, Tilly Bradshaw, a super-brilliant but innocent analyst, “The Botanist” is another beguiling M.W. Craven rocket ride. Pitted against the super-clever poisoner calling himself The Botanist, whose specialty is murdering bad folks in locked rooms, Poe also finds himself scrambling to save his forensic scientist pal Estelle, implicated in another no-escape locked-room mystery. If those descriptions signal complexity to you, let there be no mistake: this is classic, complex, clue-based genre fiction, but it comes laced with acerbic humor and dolloped out with clockwork pacing. The author flirts with plot obsession, which is what ended up turning Jeffrey Deaver’s initially pleasing thrillers into self-pastiches, but the jaunty style, the perky characters, and the controlled pacing keep the Craven engine on a steady footing. The Botanist can be read as a standalone, a most enjoyable one, but really, for a series this much fun, do yourself a favor and start back at #1, The Puppet Show.