On Her Majesty's Secret Service is the second book in what is known as the "Blofeld trilogy", which begins with Thunderball and concludes with You Only Live Twice. The story centres on Bond's ongoing search to find Ernst Stavro Blofeld after the Thunderball incident; through contact with the College of Arms in London Bond finds Blofeld based in Switzerland. After meeting him and discovering his latest plans, Bond attacks the centre where he is based, although Blofeld escapes in the confusion. Bond meets and falls in love with Contessa Teresa "Tracy" di Vicenzo during the story.