Abbie Reed, a young girl who’s lived a very sheltered life and is still coming to grips with her sister’s murder after sixteen years, has left the safety of her home back in Pembroke Pines to attend college. She’s a little overwhelmed with the whole experience and is having trouble making friends.
A couple of days before her twenty-first birthday, an old “friend” from Pembroke Pines contacts her after two years. McKenzie Thomas wants to treat Abbie to a birthday lunch and introduce her to Rocky Stern. McKenzie has exciting news: Rocky has asked for her hand in marriage and given her a knock-out sparkler.
However, McKenzie surprises Abbie with a birthday party. Since Abbie hasn’t made many friends, McKenzie has invited Abbie’s roommate, Susan, their landlord and the woman who cleans their apartment on Wednesday afternoons. McKenzie also organized a game of 21 Dares—a party challenge in which the friends plan twenty-one dares for the birthday girl to perform throughout the night. The dares will be sent one at a time as text messages to the party goers’ cell phones by a “surprise guest.”
Abbie suspects the surprise guest is her father and, at first, the party dares are harmless, silly stunts and drinking games that lead the group across the University campus and through downtown Tampa. As the night wears on, the dares turn dangerous.
When Susan is seriously injured and McKenzie disappears, Abbie learns that the “surprise guest” is someone who is connected to her sister’s murder and has orchestrated the whole night as an act of vengeance.