Young nanny Elizabeth Guiness arrives at the mansion of the brilliant, widowed scientist Richard Keaton to care for his gifted but troubled son Andrew. While trying to reunite father and son, Liz attempts to unravel the mystery surrounding the death of Richard's wife and at the same time, finds herself falling for the mysterious Keaton. Complications arise when the scientist's younger brother, Blaine, and his girlfriend, Jillian, arrive at the mansion for an extended visit.