In season two of Star Trek: The Next Generation, Captain Jean-Luc Picard (Patrick Stewart) welcomes some new faces aboard the Enterprise, including Dr. Crusher's temporary replacement, Chief Medical Officer Katherine Pulaski (Diane Muldaur), and Guinan (Whoopi Goldberg), the enigmatic bartender. The core crew evolves as they face new and unexpected challenges. Geordi LaForge is transferred from the bridge to become Chief Engineer. In a suspenseful trial, Data must prove that he is a conscious being. Riker is immersed in the warlike culture of the Klingons. And in their most dangerous battle to date, the crew takes on the Borg, a cybernetic hive mind that threatens to assimilate all intelligent life.