The Storm dropped a 109-98 National Basketball League of Canada contest to the Quebec Kebs at EastLink Arena. The game drew an announced crowd of 1,866.
Summerside played Quebec close through two quarters, and led 53-50 at the half. But the Kebs started the third quarter on a 16-5 run.
"It's been a recurring theme with us in the third quarter," said Storm head coach Joe Salerno. "If I could tell you exactly what happened in the third, it wouldn't have happened.
"We just need to continue to focus coming out of the break. The third quarter has definitely been the Achilles heel, and it's something we need to figure out."
Thursday's contest came on the heels of a 118-97 loss to the Saint John on Wednesday, a game in which the Mill Rats also scorched the Storm in the third quarter.
In the first quarter against the Kebs, Summerside's Eric Gilchrese sank his only field goal of the half to tie the game 25-25.
Julian Allen led the way for the Storm with 17 points in the half. He was the only Summerside player to score in double digits.
Quebec's Ralphy Holmes scored 15 in the first half en route to a game-high 24 points and nine rebounds.
The game became increasingly aggressive throughout the opening 24 minutes, with Quebec's Aaron Spears receiving a technical foul for throwing the ball in frustration into the courtside seats.
Storm point guard Al Stewart then took a hard foul by Shaun Fountain toward the end of the second quarter.
"It's been a recurring theme with us in the third quarter. If I could tell you exactly what happened in the third, it wouldn't have happened. We just need to continue to focus coming out of the break. The third quarter has definitely been the Achilles heel, and it's something we need to figure out." - Storm head coach Joe Salerno
Quebec head coach Rob Spon received a technical foul while arguing the call with an official.
But the Kebs channelled Spon's frustration at the start of the second half, jumping out to a 68-60 lead over Summerside midway through the third quarter.
The Storm would never regain the lead, despite Gilchrese's 14-point effort in the half. Allen would make just one field goal in the second half for a 19-point night.
Mike Williams added 15 before fouling out in the fourth quarter. Stewart also contributed 15 in the loss as the Storm shot 35-for-83 from the field.
"I don't think we got to the free-throw line in the second half like we did in the first half," said Salerno. "We weren't attacking the rim."
The loss drops the Storm's record to 5-5 (won-lost) while the Kebs improved to 7-4.
London visits tonight
The Storm will host the first-place London Lightning (7-2) today at 7:30 p.m.
"If you can't get up for the London Lightning, I don't know who you can get up for," said Salerno. "With us, it really doesn't matter who comes into our gym right now, we've got to play better basketball.
"It's tough coming into London after two losses, and we knew this was out toughest stretch of the season - three games in three nights against three good teams. Hopefully, we'll get one of the three."