A peculiar abduction in Boston leads the team to uncover details of the mysterious man known as the Observer; Walter, Peter and Astrid analyze unusual evidence and deal with Walter's insatiable appetite for milkshakes.
Kyle and Jessi search for the truth about what really happened to Sarah.
Kyle vows to stop Cassidy and Latnok when he learns of their true plans for Adam's experiment.
Kyle tries to figure out how to make things right with Jesse; Amanda and Nate's new relationship makes Kyle jealous.
Kyle begins to repay his debt to Latnok; Nicole and Stephen face huge medical bills following the accident.
