Susie Vanderhoof is an outspoken, bright eight-year-old with an imagination large enough to match her heart. She makes the discovery of a lifetime when she finds a talking spider named Tommy Tobotsky Tarantula III has been residing in her sock drawer. The two form an immediate bond, but Susie's parents think she is exercising her overactive imagination when she tries to tell them about Tommy, and then, refuse to allow her to keep him. Fearful of losing her new friend, Susie makes a brash decision that puts her and Tommy in danger, and in the process, irrevocably shifts the dynamic of her small family.