Anastajia and Beowulf are standing next to each other and they begin running north down a long, straight road.  The moment that they both start running is event A.  They both run at a constant speed, but Beowulf is running twice as fast as Ana.  After 5 minutes Beowulf starts to get lonely and he turns around and runs back toward Anastajia.  They are soon reunited and stop running.  Call this event B.

Ana and Beowulf both have watches with them as they run and they note the times at which events A and B occur.