The Milwaukee Journal Sentinel stories describe how scientists learned to reprogram cells and the Web page detailing the scope of stem cell research are based on interviews with 90 scientists, doctors and bioethicists, as well as supporters and opponents of research involving embryonic stem cells. The Journal Sentinel interviewed 15 of the scientists involved in the race to reprogram human cells.

Reporter Mark Johnson also read more than 170 scientific papers tracing the major steps toward cell reprogramming and other advances in stem cell research. With the permission of the scientists, Johnson spent about 30 hours in a lab at the Medical College of Wisconsin observing experiments involving reprogrammed cells. All reports of thoughts, feelings or conversations are descriptions that come directly from interviews with the individuals themselves.

Part One: Scientists have been in a race to control our cells and turn them into a powerful new branch of medicine. In the 1980s and 1990s, researchers captured embryonic stem cells and gained the first evidence that a mature cell could be sent back to its past.

Part Two: Two scientists begin their pursuit of an improbable goal: to harness the healing potential of an embryonic stem cell without the destruction of an embryo. In the race to the good cell, one team pulls ahead.

Part Three: More scientists join the field, attempting to send human cells back to their embryonic origin. Critical decisions determine the outcome of the quest for the good cell.