Death Note Episode 15: Wager
Episode 15 of 37 of Death Note, aired January 23, 2007, 23 minutes. Available with English subtitles and dub where released.
Episode summary
Light tries using the second Kira to find out L's real name. However, L is well prepared for Kira's next move and is able to get one of the Kira is in his custody soon enough.