This is the snapshot that Mr. Lisbon takes of the girls before they go to the prom. Note that Lux’s hand looks like she is holding a cigarette, which is how she is found when she dies. Therese’s eyes are closed, and she ends up overdosing on sleeping pills. Mary coughs right after the photo is taken, and she dies by putting her head in the oven (and, in the book, is the only one who accidentally survives). Bonnie’s arm looks like a noose around her neck, like how she commits suicide.