Castle - Season 8, Episode 9: Soundtracks

Martha rehearse a performance piece when a body is discovered in the artificial snow box.

Castle and Alexis follow the emoji instructions from Robyn's phone which leads them to a meeting of an a capella group at a warehouse.

(Song #1 sung during the riff-off) The a capella group start off the riff-off battle. 

(Song #2 sung during the riff-off) Castle notices one of the singers is wearing the same bracelet as Robyn wore; Ryan and Esposito burst into the warehouse unaware of the non-dangerous scene .

Martha rehearses a performance as a body is discovered in the artificial snow box.

Castle and Alexis follow the emoji instructions on Robyn's phone to the meeting of an a capella group at a warehouse.

The a capella group starts a riff-off.

Song #2 in the riff-off; Castle notices one of the singers has the same bracelet as Robyn; Ryan and Esposito burst into the warehouse.