The Avenue of the Dead (The Davina Graham Thrillers)

M16 agent Davina Graham plunges into a hotbed of international intrigue when she penetrates the inner sanctum of one of the US president’s top aides, and tracks an elusive criminal from the White House to Moscow to Mexico City
 
Still reeling from the murder of her husband, Ivan Sasanov, at the hands of the KGB, British Intelligence agent Davina Graham has been called back into active service to head off a potential international crisis. The British-born wife of Edward Fleming, the US president’s assistant under-secretary of state and close friend, has appealed to the British ambassador for sanctuary. Elizabeth Fleming claims that her husband tried to murder her because she found out he was passing information to the Russians. Fleming’s first wife died in a fire in their Mexico vacation home, but it was officially ruled an accident. Now the Secret Intelligence Service needs Davina to find out whether Elizabeth’s allegations are true. If so, Elizabeth’s life could be in grave danger. But it may already be too late.
 
Now a target herself, Davina follows a labyrinthine trail that takes her from the inner circles of Washington to Mexico City and a clinic in the mountains that will bring a fiendishly clever global conspiracy full circle. On the edge of uncovering the truth about two seemingly unrelated murders, she uses herself as bait to trap an elusive criminal known as the Plumed Serpent.
 
The Avenue of the Dead is the 2nd book in the Davina Graham Thrillers, but you may enjoy reading the series in any order.