NL50 TPTK raised on turn in 3way pot

[chris216]

MP is 66/18/2 over 350 hands.
Button is 33/12/2 over 140 hands. He has taken the exact same line in a previous hand where he flopped the nut flush.
What should I do on the turn?

PokerStars No-Limit Hold'em, $0.50 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Button ($112.95)
SB ($50.50)
BB ($50.45)
Hero ($100.20)
MP ($59.35)

Preflop: Hero is UTG with A[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">Hero raises to $2</font>, MP calls $2, Button calls $2, <font color="#666666">2 folds</font>.

Flop: ($6.75) 4[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $5</font>, MP calls $5, Button calls $5.

Turn: ($21.75) 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $15</font>, MP calls $15, <font color="#CC3333">Button raises to $30</font>, Hero ???