To get a grappling hook, you will need a Shrubbery, three horseshoes, and tools, all given to Braddock at the right time and in the right combination. The other items are all in the Stables, but the Shrubbery is found here. Proceed to the far upper left room and apply the Handsaw (obtained in the Stables) to the intoxicating and highly dangerous plants along the upper wall. This room is highly poisonous and very dangerous, so you must also be tough enough to survive this little expedition.