The grappling hook or grappling gun is a Providence weapon that is used to grab and hold onto ledges and objects. It appears as a regular gun with a retractable "claw".
Dr. Holiday used this weapon when trying to escape the collapse of Van Kleiss' castle. When using it, it successfully hooked onto a root that grew out of the ceiling. However it broke, causing them to fall.
- 115. "What Lies Beneath"