After being left out of a mission, Jubilee takes out her frustration by training while Professor X observes her. Little does she know, she will have to put that training to the test when Sabretooth breaks into the mansion!

While the X-Men are out on a mission, Jubilee is training in the Danger Room, observed by Professor X. She's not too pleased with her prowess. Meanwhile, Sabretooth sneaks to the mansion grounds, using his mutant powers to get past the defense systems and concentrating to hide his thoughts from Professor X's telepathy. After Sabretooth ambushes and stuns Xavier, Jubilee uses all of her training, abilities and wits to fight against the feral mutant, finally bringing him down by pushing Sabretooth onto exposed electric cables. As the X-Men arrive, they are surprised by Jubilee's victory and congratulate her on surviving the "trial by fire".