Robert Ludlum's The Bourne Vendetta

A lover from Bourne's past seeks his help when assassins threaten her husband, but only treachery burns hotter than true love.Two years ago, and with assassins after his head, Bourne knew he had to let Abbey Laurent walk away from his dangerous world. Now Abbey is back — and she's married to a top government official. But she's convinced someone is trying to kill her husband, and she wants Bourne's help. Bourne follows the plot into a deadly web of conspiracy that puts them all at risk. But the deeper he descends into the violence and duplicity, the more he believes that Abbey may not know who her husband really is...

Book 20 in the Jason Bourne series.