The episode begins with Josh kicking a ball into the air, impressed at how many times he's managed to keep it in the air. Elliot leaves for class, reminding Josh he'll be late if he doesn't get going too before leaving. Josh doesn't pay attention, only realizing a few moments later that he's running late. Josh arrives late, missing the question the class was asked to solve, with Edgar pointing out the mirror won't repeat it. Josh tries to get the question from one of the others, but they're all too busy trying to solve it.
Josh asks Elliot why he didn't warn him he'd be late, only for Elliot to point out he did warn him twice. Josh tries to look on the bright side, only to notice that Elliot has left him behind again.
While listening to a CD he got from a trade with Toby, Josh ends up being late for Tony's birthday party. Josh apologizes for being late, but Tony doesn't mind. Josh is a bit disappointed to find there's no cake left, though.
Another day, Josh is having trouble finding his sneakers before a game. He promises the others that he'll find them and make it to the game in time. However, he gets distracted when he discovers a handheld game console he thought he'd lost, and decides to play for just a few minutes. With Josh late for the game, his team ends up losing. Josh tries to apologize again, but the others are tired of his excuses.
While walking through a hallway, a beam of sunlight draws Josh's attention to a clock in the hands of a statue. Josh takes the clock and reads an inscription on the back which says that anyone who needs time can try using it. Josh decides to take it with him, to see if it might help. Josh goes to show the watch to the others, promising he won't be late again, but they're still mad at him. Josh tries showing them the functions of the clock, and discovers that it can stop time for everyone except him.
Oversleeping the next day, Josh uses the magic stopwatch to give himself some time to eat breakfast before heading to Dorothy's class, arrving just as Dorothy was about to ask where he was. Playing another game, with only five seconds to turn things around, Josh uses the watch to ensure his team gets the point they need to win. However, after the ball game, Josh feels something is off with his arm. He asks Gertrude to take a look at it, noting that he seems to have pulled a muscle. She notes that it's odd for someone Josh's age to end up with such an injury, noting that the only other time she saw a similar one was on a eighty-year old.
Elliot soon starts to notice that something is off, as Josh seems to start having memory issues and difficulty hearing. Later when he bumps into Victoria, she is confused by his odd behaviour, before noticing he has a gray hair. She goes to the others to explain what she saw, but Janice doesn't see the big deal. Elliot notes that he too has noticed Josh acting strangely, but the others eventually dismiss it as nothing serious.
Josh's hair is looking even grayer while he plays a game of chess against Toby. When he uses the watch to cheat at the game, Toby is shocked to see Josh having turned into an old man. While following him, Josh discovers what has happened to him when he sees his reflection in a mirror. He realizes it must be because of the watch, before collapsing and dropping the watch.
An aged Josh later enters the kitchen where the others are having lunch, not recognizing the others. The kids try to figure out where the old man came from, before Toby rushes in to tell everyone what has happened to Josh. Everyone realizes that the old man is Josh, and try to figure out what happened to him and how to reverse it.
After discussing a few possible causes, Janice and the others realize it must be the stopwatch. Malcolm realizes it was Sir Hour's watch, and explains how it works. Everyone begins searching for the watch while Josh sleeps. As they search for a while without luck, Elliot suggests they call it a day and continue the search the day after, but Janice refuses, pointing out that this whole situation is likely their fault for giving Josh such a hard time over being late all the time.
A beam of light from the setting sun outside makes the watch shine from under the desk it rolled under earlier, allowing Janice to notice it. They bring the watch back to Josh, and try to figure out how to return Josh to his true age. Janice figures that they probably need to wind it backwards, and Elliot tells her to put the watch in his hand. Josh gradually starts to turn younger, until he's back to his original age and they stop the clock.
With Josh back to normal, they try to wake him up, with Elliot managing to wake him up by telling him he's going to be late. Josh doesn't remember what happened to him, and asks if he's late for class. The others assure him he's not, telling him he's got all the time in the world.
