Frank Longbottom was an Auror. Along with three others, Barty Crouch Junior was convicted after the First Wizarding War of torturing Frank and Alice using the Cruciatus Curse. Frank was captured by the witch and wizards and subjected to the Curse, as they believed he had information about Voldemort's whereabouts. Alice was also tortured with the Cruciatus Curse after they were unable to extract information from her husband.
Frank and Alice Longbottom survived the incident, but were rendered insane by the torture. They live in St Mungo's Hospital for Magical Maladies and Injuries. They are visited by their son Neville and his grandmother during the holidays, but they do not recognise him.
Frank and Alice Longbottom live in the Janus Thickey Ward at St Mungo's, a ward for those with permanent spell damage. Augusta Longbottom, Frank's mother, tells Harry that the couple were very well respected within the wizarding community, and highly gifted Aurors before they were tortured to insanity by Lord Voldemort's supporters.
Alice Longbottom edges down the ward in her nightdress towards Neville, Augusta, Ginny, Harry, Ron and Hermione. She no longer has the plump, happy-looking face as she did in the photograph of the original Order of the Phoenix; her face is thin and worn, her eyes seem overlarge and her white hair is wispy and dead-looking. She makes timid movements at her son as she reaches the group, and drops an empty Drooble's Best Blowing Gum wrapper into his hand. She totters away back up the ward, humming to herself.