NL 20 QQ face 4bet vs unknown

[Kukla]

I have some trouble to play such situation vs unknown villain [img]/images/graemlins/frown.gif[/img]

iPoker No-Limit Texas Hold'em (NL20), $0.20 BB (6 handed) SilverKitty Hand History converter by www.pokeronline.com.ua

Hero($21.83)
CO ($40.56)
Button ($20.51)
SB ($58.36)
BB ($20)
MP2($19.38)

SB: Post SB $0.10
BB: Post BB $0.20

Preflop:
Hero is MP3 with Q[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/club.gif[/img]
<font color="#CC2222">MP2 Raise $0.6</font>
<font color="#CC2222">Hero Raise $2.4</font>
<font color="#666666">4 folds</font>
<font color="#CC2222">MP2 Raise $5.2</font>
Hero ?