Editor's note: This episode replaces a previously scheduled episode.

LEONARD AND SHELDON ARE FORCED TO MAKE A BLACK MARKET PURCHASE IN ORDER TO COMPLETE AN EXPERIMENT, ON A REBROADCAST OF "THE BIG BANG THEORY," MONDAY, APRIL 25

Michael Rapaport Guest Stars as Kenny, a Black Market Dealer

"The Helium Insufficiency" - In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need. Also, Penny and Bernadette download a dating app on Amy's phone to try and find her a new man, on a rebroadcast of THE BIG BANG THEORY, Monday, April 25 (8:30-9:00 PM, ET/PT), on the CBS Television Network. Michael Rapaport guest stars Kenny, a black market dealer. (Originally broadcast 10/26/15.)

REGULAR CAST:

Johnny Galecki (Leonard)
Jim Parsons (Sheldon)
Kaley Cuoco (Penny)
Simon Helberg (Wolowitz)
Kunal Nayyar (Koothrappali)
Mayim Bialik (Amy)
Melissa Rauch (Bernadette)

RECURRING CAST:

Kevin Sussman (Stuart)
John Ross Bowie (Barry Kripke)

GUEST CAST:

Michael Rapaport (Kenny)
Elena Campbell-Martinez (Maria)

WRITTEN BY: Steve Holland, Maria Ferrari and Anthony Del Broccolo

TELEPLAY BY: Steven Molaro, Eric Kaplan and Jim Reynolds

DIRECTED BY: Mark Cendrowski