Tom Wilson hustled to keep the puck in along the left half wall, rolling it behind the Boston cage. Conor Sheary put some heat on Boston blueliner Charlie McAvoy, causing him to lose his edge as he tried to spin away with the puck. Anthony Mantha collected it and - from below the goal line - he put a perfect feed to the front for Alex Ovechkin. The Caps captain put it home for a 1-0 Washington lead at 8:21 of the second.
Washington's lead was short-lived. Boston kept a puck in at the Caps' line, and Washington's coverage went all askew. Taylor Hall got behind all five Caps skaters, and when Smith fed him, Hall was able to chip a shot over Samsonov's shoulder to make it a 1-1 game at 9:17.
Late in the middle period, Washington regained the lead on a forechecking goal from Nic Dowd. Dowd laid a big hit on Boston's Charlie Coyle along the right half-wall in the Bruins' zone, blunting the center's exit attempt and enabling Garnet Hathaway to keep it in the zone at the left point. Behind all five black-sweatered skaters on the ice, Dowd went to the net. Hathaway put it right on his tape, and Dowd redirected it past Rask for a 2-1 Washington lead at 18:15.
Eleven minutes into the third, Dowd went off for hi-sticking McAvoy behind the play, sending the Caps to a fifth penalty killing mission, the first time they've had to face as many as five shorthanded situations in a game since Feb. 20, a span of 42 games.
On the ensuing Boston power play, the Bruins evened the game again, getting the tying tally from Marchand some 32 seconds after Dowd was seated. Marchand whacked a shot home from just off the right post, seconds after missing an opportunity from the same spot.
Late in the frame, the Caps were buzzing the Boston end in a bid to go back on top, and they generated a number of excellent chances. Two of them - one off the stick of Nicklas Backstrom and the other off the blade of Wilson - rang the iron, sending the game into overtime.
In the first overtime, Boston was buzzing early while Washington had a couple of looks late, but the Bruins easily had the better of the possession battle. Samsonov had to stop a pinballing puck in the first half minute - Boston wasn't even credited with a shot on the play - and he made an aggressive cover in the second minute to stop an offensive zone shift for Boston and get a draw for the Caps.
Samsonov's best stop of the first overtime came at 13:46 after the Caps got stuck in their own end, unable to get a clear in a period with the long change. Samsonov thwarted David Pastrnak from the top of the paint at 13:46 to prolong the game.
Pastrnak had another narrow miss in the second overtime, shortly before Smith ended the game.
"We have a plan in place to try to play behind their [defense]," says Bruins coach Bruce Cassidy. "When we get away from it, we get into a little bit of trouble, so we'll keep sending that message.
"You don't expect to get those, but if you keep playing behind their [defense] and forcing them to break pucks out, you will get some breaks like that. [Smith] stayed on it, and good for him to have the recognition to stuff it."
After winning Game 1 of the series on Dowd's overtime goal, the Caps have dropped two straight games in which they held a one-goal lead in the third period.
"I think we did some good things tonight, obviously it was a battle," says Wilson. "It's never easy to lose one in overtime when you're out there battling, but review it, turn the page, next game is huge."