Watson is thrown into a detective case when he is unsure whether the patient he is treating for one of the most rare ailments in the world, alien hand syndrome, is guilty of pushing his brother in front of a bus to his death.

When part of the team falls ill after becoming targets of a sinister plot, it becomes an all-hands-on-deck situation to save them before it's too late. Meanwhile, Watson announces a new ambitious project that he has been working on, on the two-part season finale.