Trilby's Grolly is his trademark burgling tool. At first glance it appears to be an ordinary blue umbrella, but it houses a powerful grappling hook launcher capable of hooking onto ledges, allowing Trilby to climb up walls and swing across gaps. The tip of the Grolly also has a powerful taser capable of knocking people out in one hit, allowing him to silence anyone who catches him off-guard without killing them. It only has enough battery power for three hits, so Trilby has to make not to use it unless absolutely necessary.
The name "Grolly" is a portmanteau of "grapple" and "brolly", a British slang term for an umbrella.