The idea that occurred to me and Hodgins was maybe a bullet made of ice. Such a bullet would explain why it left no trace or exit wound - it melted in the heat of the body - but alas it turns out that a bullet made of frozen water would not be able to break the skin.
Another symptom provides a clue. After Bones comes back from her first flatlining, she nearly dies again - some kind of allergic reaction. But to what? Hodgins figures out that it's an antibody reaction to someone else's blood in Bones' system. And he has the answer: the bullet was not frozen water but frozen blood. As a last touch, Bones volunteers for surgery to get a precise ID on the antigen inside her, so her would-be killer (and killer of a security guard at the Jeffersonian) can be nabbed. Bones literally puts her body on the line - or on the table - to get the bad guy
As I said, an excellent mystery story. But the magic bullet is really magical in a different way. In Bones' near encounter with death, she sees and talks to her late mother. (The history of Bones and her parents is worth reading up on if you haven't seen the first few seasons - it's a great story.) Her mother now tells Bones that she has to let out some of the little girl kept locked deep inside all of these years - locked inside, so Bones with her brilliant indomitable logic could get in control of her nearly shattered life and succeed. But for Bones to lead a truly full and happy life - which all who love her want for her - she has to live with more emotion.
This puts a fine bow on tonight's story. Bones is at the Jeffersonian, working in the wee hours, because she and Booth got into argument over Bones' scientifically logical dissection and analysis of every aspect of their lives, including having fun with baby Christine. This is something Bones and Booth have been struggling with all season. It takes Bones almost dying to get her to see that she needs to be more spontaneous. But spontaneity is, after all, not easy for anyone to learn.
If someone asks you to be spontaneous, how can you comply? If you then try to be spontaneous, you're actually not being spontaneous, because you're following an instruction. In the case of Bones, it took a magic bullet for her to break out of this be-spontaneous paradox.
See also Bones 8.1: Walk Like an Egyptian ... Bones 8.2 of Contention ... Bones 8.3: Not Rotting Behind a Desk ... Bones 8.4: Slashing Tiger and Donald Trump ... Bones 8.5: Applesauce on Election Eve ... Bones 8.6: Election Day ... Bones 8.7: Dollops in the Sky with Diamonds ...Bones 8.8: The Talking Remains ... Bones 8.9: I Am A Camera ... Bones 8.10-11: Double Bones ...Bones 8.12: Face of Enigmatic Evil ... Bones 8.13: Two for the Price of One ... Bones 8.14: Real Life
And see also Bones 7.1: Almost Home Sweet Home ... Bones 7.2: The New Kid and the Fluke ...Bones 7.3: Lance Bond and Prince Charmington ... Bones 7.4: The Tush on the Xerox ... Bones 7.5: Sexy Vehicle ... Bones 7.6: The Reassembler ... Bones 7.7: Baby! ... Bones 7.8: Parents ...Bones 7.9: Tabitha's Salon ... Bones 7.10: Mobile ... Bones 7.11: Truffles and Max ... Bones 7.12: The Corpse is Hanson ... Bones Season 7 Finale: Suspect Bones
And see also Bones 6.1: The Linchpin ... Bones 6.2: Hannah and her Prospects ... Bones 6.3 at the Jersey Shore, Yo, and Plymouth Rock ... Bones 6.4 Sans Hannah ... Bones 6.5: Shot and Pretty ... Bones 6.6: Accidental Relations ... Bones 6.7: Newman and "Death by Chocolate" ...Bones 6.8: Melted Bones ... Bones 6.9: Adelbert Ames, Jr. ... Bones 6.10: Reflections ... Bones 6.11: The End and the Beginning of a Mystery ... Bones 6.12 Meets Big Love ... Bones 6.13: The Marrying Kind ... Bones 6.14: Bones' Acting Ability ... Bones 6.15: "Lunch for the Palin Family" ...Bones 6.16: Stuck in an Elevator, Stuck in Times ... Bones 6.17: The 8th Pair of Feet ... Bones 6.18: The Wile E. Chupacabra ... Bones 6.19 Test Runs The Finder ... Bones 6.20: This Very Statement is a Lie ... Bones 6.21: Sensitive Bones ... Bones 6.22: Phoenix Love ... Bones Season 6 Finale: Beautiful
And see also Bones: Hilarity and Crime and Bones is Back For Season 5: What Is Love? and 5.2: Anonymous Donors and Pipes and 5.3: Bones in Amish Country and 5.4: Bones Meets Peyton Place and Desperate Housewives and Ancient Bones 5.5 and Bones 5.6: A Chicken in Every Viewer's Pot and Psychological Bones 5.7 and Bones 5.8: Booth's "Pops" and Bones 5.9 Meets Avatar and Videogamers ... Bad Santa, Heart-Warming Bones 5.10 ... Bones 5.11: Of UFOs, Bloggers, and Triangles ... Bones 5.12: A Famous Skeleton and Angela's Baby ... Love with Teeth on Bones 5.13 ... Faith vs. Science vs. Psychology in Bones 5.14 ... Page 187 in Bones 5.15 ...Bones 100: Two Deep Kisses and One Wild Relationship ... Bones 5.17: The Deadly Stars ...Bones Under Water in 5.18 ... Bones 5.19: Ergo Together ... Bones 5.20: Ergo Together ... Bones 5.21: The Rarity of Happy Endings ... Bones Season 5 Finale: Eye and Evolution