[Bruce and Alfred try to solve Riddler's Clues]

"We're five little items of an every day sort; you'll find us all in a tennis court". In...a...E, I, O, U. Vowels.

Not entirely unclever, sir. But, what do a clock, a match, chess pawns, and vowels have in common? What do these riddles mean?

Every riddle has a number in the question and they write in this order: 13, 1, 8, and 5.

13, 1, 8, and 5.

Maybe, perhaps, letters of the alphabet?

Of course, 13 is M.

1 would be A, 8 would be H, and 5 would be E.

M-A-H-E...

Perhaps 1 and 8 are...18?

18 is R. M-R-E.

[makes a realization]

How about "Mr. E"?

"Mystery".

And another name for mystery?

Enigma.

"Mr. E-nigma". Edward Nygma. Stickley's suicide was obviously a computer-generated forgery.

You really are quite bright, despite what people say.