Check Check Raised

So far villain has played reasonably tight preflop and nothing special post flop but we haven't played many hands together. The check on the river from him (after checking the turn) led me to believe my hand was good, but the check raise all in from villain caught me totally off guard. Is this a call or a fold? How is my line, standard?

Party Poker No-Limit Hold'em, $ BB (6 max, 5 handed)

Hero ($75.02)
Button ($41.35)
SB ($24.65)
BB ($39.75)
UTG ($50.20)

Preflop: Hero is MP with K[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/spade.gif[/img]. SB posts a blind of $0.25.
<font color="#CC3333">UTG raises to $1</font>, <font color="#CC3333">Hero raises to $3</font>, <font color="#666666">3 folds</font>, UTG calls $2.

Flop: ($6.75) J[img]/images/graemlins/diamond.gif[/img], 2[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
UTG checks, <font color="#CC3333">Hero bets $4</font>, <font color="#CC3333">UTG raises to $8</font>, Hero calls $4.

Turn: ($22.75) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
UTG checks, Hero checks.

River: ($22.75) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
UTG checks, <font color="#CC3333">Hero bets $15</font>, UTG calls $39.20 (All-In)