The Third Wheel is a romantic comedy about a man named Stanley trying to score the new girl at his work named Diana. Falling for her at first site Stanley vows to ask her out. She is the new girl in the office but doesn't know he exists. A year passes and finally Stanley finds Diana is single again. Stanley is urged to face his fears and is pushed into asking Diana out by his best friend and coworker Michael. Stanley tries to gain his confidence as the entire office encourages him to go for it. Unable to stifle his fear Stanley crashes into Diana almost blowing his chances. Charming her with a witty joke Stanley scores a date with his dream girl. He has planned every detail of his perfect date with his perfect girl and attempts to reenact his fantasy. While Stanley dreams of his date, Michael starts a bidding pool with their coworkers to see how well Stanley's date will really go.
Stanley and Diana start their date off with drinks and an average start. Unknowingly being watched by some of their spying coworkers. Stanley and Diana leave from drinks heading to the next step of their date only to have Stanley hit a homeless man with his car. Stanley tries to apologize to this homeless man named Bill, and tries to pay him off. Stanley thinks his entire date has been ruined and that his chances with Diana lost. Trying to do the right thing by Bill, and trying to save his date with Diana, Bill becomes a constant "Third Wheel". Hilarious calamity occurs at every turn as Stanley tries to woo Diana and make things right with Bill. No matter how hard Stanley tries his efforts never go quite as planned, but his night isn't a total loss. Stanley finishes his night off with a bout of truth and honesty possibly saving his night.