Fortunately, House has come up with a brilliant plan to test for tainted blood. He rolls up his sleeve and tells them to inject him with blood from the same donors who were used during Flynn's surgery. I'm not sure if that's even possible or accurate, since the blood could have been tainted after it came from the donor and before it was given to Flynn. But House is the same blood type as Flynn and he's got a death wish, so let's go!
Thirteen gets to set up the transfusion, which gives House the chance to ask her more about her stupid Mystery. He stole her wallet and saw a picture of a young woman in it he thinks is Thirteen's mother. The reason why she's so young in the picture, House guesses, is because she died young. That would also explain why Thirteen keeps a picture of her mother in her wallet. I mean, I love you and all, Mom, but I have to save my wallet space for the seventeen grocery-store club cards I have to get and my driver's license. Also, all my dollah dollah bills. Thirteen shrugs off her mother's death, saying Grover Cleveland is dead, too. Oh, but is he? Could this be leading up to a seven-episode story arc about a Zombie Grover Cleveland, played by special guest star James Gandolfini? Or are we just going to learn more about stupid Thirteen, like how her mother's obituary, which House Googled (I guess he entered "Thirteen mother dead obit" and got lucky), said she died after a long illness that I'm sure was fought bravely. I'll bet it also said "Twenty-Nine leaves behind her loving husband, Fifty-Seven, and daughter, Thirteen."