Gary Greenberg opens his new history of depression with a riveting tale of scientific ingenuity. A young, unknown marine biologist with an interest in mussels happens to discover the neurotransmitter serotonin and helps spur the antidepressant revolution. Lest we get too excited, though, Greenberg deflates our hopes just a few pages in. Great science stories involve chance discoveries that change our everyday lives, he says—but this is not the kind of story he is going to tell.