Penn, Boone, and Sashi have to help the dragons of Wingfire Academy in a battle against a new enemy: the unicorns!
The trio return to the dragon world which finds itself under attack by unicorns who threaten to destroy their dimension. However before they fight them, they must get Blaze, who has fallen into a slump from a previous defeat from the unicorns, back on his feet to help them.
This is the first time someone other than Sashi or Larry explains the mission.
The title "Alpha, Bravo, Unicorn" refers to the use of the words "Alfa [sic], Bravo, Charlie, etc.," to represent the letters A, B, C, etc., in the "International Radiotelephony Spelling Alphabet"; this alphabet was devised to enable military radio operators to use different sounding words to represent letters which might be confused because they sound similar over a radio. (Thus if a radio operator had to specify something unfamiliar to the person he was talking to, such as a town named "Debraszaville," rather spelling it confusingly "D, E, B, R, A, S, Z, A, V...," etc., he would spell it "Delta, Echo, Bravo, Romeo, Alfa, Sierra, Zulu, Alfa, Victor..." etc.). "U" in this alphabet was actually represented by the word "Uniform" rather than "Unicorn."