I figured this out on my ukulele, so sorry for any mistakes, but I think it sounds about right.
Especially since she played it on a keyboard. Enjoy! ^-^
[Verse]
Am
Deerstalker at the ready.
Dm
Careful, feeling unsteady.
E7 Am
Must be the poison in my blood.
Am
Taxi, I'm in a hurry.
Dm
Watson, no need to worry.
E7 Am
Gadzooks! Irene is in the nud!
[Chorus]
Am G D
I am sherlocked,
Dm F Am
Cannot stop.
Am G D
Waiting, watching.
Dm F7 Am
Til the penny finally drops.
[Verse]
Am
Lestrade! The clue's right there look!
Dm
Something that you have mistook!
E7 Am
You see, but you do not observe.
Am
Oh no, it's Moriarty
Dm
Beat him, let's have a party.
E7 Am
By jove! He's back he's got a nerve!
[Chorus]
Am G D
I am sherlocked,
Dm F Am
Cannot stop.
Am G D
Waiting, watching.
Dm F7 Am
Til the penny finally drops.
[Bridge]
Am
Molly, completely smitten.
Dm
What's that? A glowing kitten?
E7 Am
Sorry, but rabbit wouldn't scan.
Am
Big heist and daring bank raids,
Dm
Friendships, farewells to be made.
E7 Am
Sherlock, you'd better have a plan.
[Chorus]
Am G D
I am sherlocked,
Dm F Am
Cannot stop.
Am G D
Waiting, watching.
Dm F7 Am
Til the penny finally drops.