Debra Winger has been AWOL from the Hollywood mainstream for so long that any appearance marks a cause for celebration. But this Lifetime TV movie proves an uneven comeback vehicle for the onetime Oscar nominee. For three-fourths of its running time, Dawn Anna plays as a heartwarming, motivational drama about a single mother who overcomes economic obstacles and a rare brain condition to emerge as a fantastic parent, teacher, and coach. The script, co-written by director Arliss Howard, does suffer from a tendency toward sentimentality. But the grit, intelligence, and self-deprecating wit of Winger's performance keep her character from becoming a one-note saint -- and the film from becoming an uplifting bore. Things take a sharp left turn, however, when we find out why Howard became fodder for a biopic in the first place -- her involvement in the 1999 massacre at Colorado's Columbine High School. Whereas other, fictionalized treatments of Columbine focus on the massacre itself, Dawn Anna succeeds in involving the audience deeply in the lives of its characters before unleashing a national tragedy on them. Unfortunately, once the tragedy comes, the script resorts to uplifting clichés that overshadow the more authentic emotions of the first two acts.