Don sets about learning the protocols of becoming a father, but his unusual research style gets him into trouble with the law. Fortunately his best friend Gene is on hand to offer advice: he's left Claudia and moved in with Don and Rosie.

Picking up where The Rosie Project left off, The Rosie Effect is a fun, hilarious, and poignant read. "Don Tillman helps us believe in possibility, makes us proud to be human beings, and the bonus is this: he keeps us laughing like hell" (Matthew Quick, author of The Silver Linings Playbook).