According to her friends, Lucy Lancaster, Austin, Texas genealogist, has never been drunk. Tipsy, sure, but drunk? No way. So when she arrives back at her office from a three-martini lunch a few sheets to the wind, it's a notable occasion. Even more momentous is what her client, Austin billionaire Gus Halloran, has announced on live television with a blotto Lucy standing at his side: Texas senator Caleb Applewhite might be responsible for the murder of Seth Halloran.

Of course, Lucy is a genealogist, so the murder in question took place back in 1849. And it's possible that another nineteenth-century Texas politician may, in fact, have wielded the death blow. Lucy is determined to prove beyond a shadow of a doubt who the guilty man is, but when her curiosity lands her at the scene of another murder - this time, in the present-day - she realises that the branches of some family trees shouldn't be shaken.