Truman's fourth mystery takes on yet another Washington institution--though with more affection than satire--so there's a good deal of Smithsonian history/sightseeing mixed in with the chatty, busily unconvincing mystery here. Lewis Tunney, preeminent scholar of post-Revolutionary secret societies, turns up dead at the Smithsonian, killed with Tom Jefferson's sword. . . just after telling the VP that something scandalous is going on at the museum. And the murder's mixed with robbery: a Legion of Harsa medal has been stolen! So D.C.'s Inspector Hanrahan is soon sleuthing busily--as is Tunney's fiancÃ‰e Heather McBean, whose recently-dead uncle (suicide? murder?) was a Legion of Harsa expert/collector. Meanwhile, a loony threatens to blow up the Smithsonian; more dead bodies surface (two in England, where Tunney learned his Big Secret); assorted museum officials are revealed to have sexual secrets; someone tries to kill Heather; it's increasingly clear that some sort of black-marketing of museum treasures has been going on. And finally, after Heather seems to fall into the clutches of the villain (an over-obvious red herring), she falls into the clutches of the real, not-very-surprising villains. Warmed up a bit with Hanrahan's gentle romantic yen for Heather: a messily plotted, repetitiously talky, not-unpleasant diversion--which will benefit, as before, from the Truman byline.