Smartphones... GPS... Social media... None of it would exist if it weren't for one thing: computer technology.

So what if the computer hadn't been invented at all? Or was invented somewhere... else? BY someone else?

Kristen and Brad are visiting the University of Pennsylvania with their cousin Sally. The teens don't expect their tour to include time travel, and yet when they walk into a campus building, they find themselves in another era.

They know that the first 'real' computer was built at the university. Could that achievement be part of the reason for their trip through time? And what do the Nazis have to do with it?

This is the fourth book in the Timekeepers series. Target audience is ages 11 and up.