Monica, Tess, and Andrew celebrate Monica’s one-hundredth assignment with a cake in a park.  In the same park Audrey, a single mother who writes commercial jingles, celebrates her son Petey’s birthday.  Petey tries to blow out his candles but is racked with coughing, an effect of his disease, Cystic Fibrosis.  Monica arrives at Petey and Audrey’s home as a prospective border and she meets Celine, Petey’s best friend who is Celine Dion’s number one fan.  Celine introduces Monica to Audrey and Monica moves into their home.

Petey plays a song for Monica on tape that Audrey began to write when Petey was born but has since been unable to finish.  When he collapses on his way home from school, Petey is rushed to the hospital where, upon his release, he and Celine overhear some nurses saying he doesn’t have much time left to live.  Petey tells Audrey, who is having trouble accepting the fate of her little boy, that when he dies, he wants to die at home.  Petey, with Monica’s help, begins to compile a list of the things he wants to do before he dies.  His items include: Learn to play the piano, find a home for Fluffy (his pet iguana), find someone to sing with Mom, find someone to shovel the snow.

With Tess and Andrew’s help these things come to pass (Tess agrees to take care of the iguana).  Petey and the angels move on to the more tricky items on the list, including introducing Celine to the real Celine Dion.  Celine is blindfolded and taken to a concert hall to meet Celine Dion in her dressing room before the show.  Celine Dion tells Petey and Celine, who is in shock, that she will sing a special song for them.  Later during the concert she sings “Love Can Move Mountains” to the children.  At the end of the concert Petey becomes very sick and, at the hospital, Audrey comes to the realization that Petey will soon die.

Celine, with Tess’ help, resolves to help make it possible for Petey to die at home, another item on his list, and they visit the HMO in hopes of getting a medical waiver allowing this.  When they are denied Tess demands to see the manager, who happens to be Celine’s father.  When he says he cannot make an exception to a rule, even for Petey, Celine returns to his office in a gown and pearls, and sings “Love Can Move Mountains.”  She pleads with her father to prove he loves Petey and he pulls some strings.  Petey is brought home and, while he sleeps, Audrey discovers his list, including the wish that Audrey would finish her song.  Audrey tries to finish the song, but breaks down in tears when she can’t get past the first verse.

Monica reveals herself to Audrey, comforts her, and asks her to tell the whole world about Petey’s love with her song.  Audrey works all night to finish the song, and in the morning wakes Petey, telling him to cross that item off his list.  Petey is taken outside to find many neighbors gathered to perform Audrey’s finished song, “The 151st Psalm,” the main chorus of which proclaims, “For as long as I shall live I will testify to love!”  Petey tells Andrew, “It is finished,” and the young boy dies as the crowd continues to sing his song.  Monica crosses the final item off of Petey’s list: “Go to Heaven.”