Susannah "Beck" Fisher was the mother of Conrad and Jeremiah Fisher and the wife of their rather estranged father Adam Fisher. She was the rock that everyone seemed to desperately cling to, being a second mother figure for Belly and the best friend of Laurel. She dies after The Summer I Turned Pretty but before It's Not Sumer Without You, a result of her long battle with cancer. Throughout her time alive, she is shown to be very friendly, loving as well as very compassionate.
She married her husband Adam and is shown to haved loved him very much. Despite Adam treating her horribly (drinking, regularly cheating on her, never helping her out and sometimes even mistreating their boys) she had refused to leave him, even when Laurel begged her for the sake of her own happiness. The couple finally divorced and Adam left their family by The Summer I Turned Pretty. He makes a phone call, but other than this makes no apperance. Even near death with cancer and her husband leaving her, she is lively and upbeat with her family and loved ones. She refuses to spend what she knows to be her final days in a hospital bed, but with friends and family. She finally admits her cancer has come back with a vengeance in the end of the first novel, but states that she wants to be with her family to the end of things. Despite her strong spirit, she finally dies between the first and second novels.
Her death serves as a strong and vicious blow to everyone, causing them all to struggle to live without her. It takes them about a year to form a life without her existence and to get their act together in order to move forward in their lives. She remains heavily remembered by her family and friends throughout the rest of the series. Her calming force is referenced to and used by all the characters as they navigate through their different situations in their lives.
It is discovered she left letters to "the summer kids" in the final book (although the reader only gets to read the letter she left for Belly) to read on their wedding days. It is, however, mentioned that in Conrad's letter she had written how she had seen him truly in love only once; which was with Belly.