A gifted coloratura soprano, Cook sang a wide repertoire that encompassed English, German, French, and Italian opera from a variety of musical periods.
However, this performance did not excite the attention that Cook was hoping for and she was forced to take work outside of music for the next several years while continuing with further studies with Williams, and Nicola Palumbo in New York City.
[1] In 1976 Cook made her debut with the Royal Opera at Covent Garden as Gilda in Verdi's Rigoletto, and that same year returned to that house to appear as Rachel in the world premiere of Henze's We Come to the River.
[1] During this time she added to her repertoire such roles as Catherine in L'étoile du nord, Giulietta in Bellini's I Capuleti e i Montecchi and Leila in Bizet's Les pêcheurs de perles.
Cook continued to remain active in opera houses throughout Germany until 1985 when she moved back to the United States after marrying pianist Ronald Marlowe.
In 1982 she sang the role of Angel of Bright Future in the world premiere of George Rochberg's The Confidence Man at the Santa Fe Opera.
She also notably sang the role of The Soprano in the world premiere of Anton Ruppert's ...die Siebte at the Bayerische Staatsoper in Munich, Germany, and portrayed Tania in Luigi Nono's Al gran sole carico d'amore at the Frankfurt Opera.