Alice Chesterton (Olive Thomas), is described as a "Baby Vamp" by the social set and engaged to boring Tom Carey. She flirts with many of the male guests idling at the Ives' Long Island house party, then encourages Terence O'Keefe, a playboy polo player from Ireland in New York to purchase horses for the British army, to rendezvous with her in the city, they are seen together at the "Midnight Frolic." Because of this, Mrs. Ives convinces Alice's newly-arrived sister Betty to look after Alice. Betty arranges for Terence to find her in an auto wreck where he revives her with a kiss. Genuinely in love with each other, they plan to marry, until the jealous Alice tells Betty that Terence "ruined" her. When Betty accuses Terence, he makes Alice confess her to her lies. Tom, encouraged by Terence's advice, overwhelms Alice with his "caveman" tactics. At the end, the servants, who have observed the upstairs activities, emulate their masters' flirting mannerisms.