A half-term holiday reunites Julian, Dick, Anne, George and of course Timmy, giving them time for a hiking tour. Hoping to make sleeping arrangements at farmhouses and inns, the children set off, only to have their plans interrupted by Timmy, who foolishly chases a rabbit and injures himself. George insists on him being seen by a Vet, and the children split up, only to be plunged into a new thrilling adventure.