Dr. Sarah Halifax decoded the first-ever radio transmission received from aliens. Thirty-eight years later, a second message is received and Sarah, now eighty-seven, may hold the key to deciphering this one, tooif she lives long enough.

A wealthy industrialist offers to pay for Sarah to have a rollback a hugely expensive experimental rejuvenation procedure. She accepts on condition that Don, her husband of sixty years, gets a rollback, too. The process works for Don, making him physically twenty-five again. But in a tragic twist, the rollback fails for Sarah, leaving her in her eighties as the second message arrives.

While Don tries to deal with his newfound youth and the suddenly vast age gap between him and his wife, Sarah struggles to do again what shed done once before: figure out what a signal from the stars contains before she dies.