Bruce Willis makes his third and final series appearance as Paul, the father of Ross' college-age girlfriend, Elizabeth (Alexandra Holden) -- and the current amour of Ross' former sweetie Rachel (Jennifer Aniston). As Paul's behavior becomes stranger and more ominous, Rachel begins to see her relationship with Ross (David Schwimmer) in a whole new light. Meanwhile, Chandler (Matthew Perry) enlists the aid of Phoebe (Lisa Kudrow) in choosing an engagement ring for Monica (Courteney Cox)...a major mistake! ~ Rovi