On July 9th, Hoshi Sato turns 29 and a party, complete with hot fudge sundaes, is held. Malcolm Reed arrives late and refuses the ice cream, but is eventually cajoled into having some. When he suffers some medical distress, it is revealed by Dr. Phlox that Reed suffers from a condition known as lactose intolerance.
The following day, Captain Jonathan Archer is contacted by Admiral Gardner. The Nereid Medical Academy wants to hold its immunology rotation on the Enterprise, for its resident medical students. The class is a small one. The professor, who will only be staying for a short while, is Bernie Keating-Fong, a foremost expert on rare and extinct diseases. The students are Blair Claymore, Pamela Hudson, An Nguyen, Will Owen and Mark Stone. The program is very competitive.
Travis Mayweather suggests a competition with Reed and Trip Tucker - they will each romance one of the three female students and 'whoever gets the girl first wins'. When they later meet the students, they learn that An Nguyen is a man, and Bernie Keating-Fong is a woman, but she is married. In order to make the game fairer, they drop the idea of assignments and allow any of the three of them to romance either of the two female students, Blair and Pamela. Both are lovely, but Pamela has an air about her that seems dangerous.
Pamela hooks up with the man who sends her anonymous Shakespearean sonnets – Malcolm. Everything moves very quickly, and Pamela reveals that she is into some unconventional sexual practices, including light bondage. Further, it is revealed that she was the victim of childhood sexual abuse.
At the same time, members of the crew begin to become ill with a mysterious ailment that threatens to incapacitate all of the humans on board. When Reed does not become ill, he is studied, and it is learned that his immunity is acquired, as a part of the vaccinations that he received upon joining Section 31. The disease is a form of germ warfare.