Sam (Jimi Mistry) and Alice (Jennifer Love Hewitt) Holbrock are a happily married couple living in the UK. As part of a drunken bet with her sister Felicity (Kate Miles), Alice sends Sam an anonymous Valentine's card to see if he will hide it. When he does, what started off as a silly prank ends up with Alice finding out that Sam already has a mistress, which puts her marriage at risk.