Tonight’s Boston Bruins game at TD Garden will be must see hockey.

Huh? A Monday night B’s tilt in early December? C’mon, what’s the catch.

The catch is simple – former Bruins coach Bruce Cassidy is back in town, but now as the head coach of the visiting team, the Las Vegas Golden Knights.

Cassidy was caught off guard last June, let go as the B’s head coach after replacing Claude Julien in early February of 2017, two days after the Patriots famous “28-3” Super Bowl in Houston.

All Cassidy did was take the B’s to the playoffs every season as coach, and to a seventh game at the Garden in the Stanley Cup Finals in 2019. But the Bruins were ousted in the first round in seven games last season by the Carolina Hurricanes, and in the weeks that followed, there were whispers something was up. First, team president Cam Neely did his best Harry Sinden impersonation in dropping a couple of lines or two at the press conference that the coaching needed to be tweaked. Not a good sign.

And depending on who you talk to or read, Cassidy was given assurances his job was safe until GM and perhaps his biggest ally in the organization, Don Sweeney, rang his door to tell him he was canned. He had been with the organization in either an AHL or NHL capacity since 2008.

The deal? Bruins players thought he was too tough and demanding, and there was talk that was why usual nice guy Patrice Bergeron was seriously considering retirement. It didn’t seem like a coincidence that with Cassidy gone, Bergeron came back.

Oh the poor babies.

The players got what they wanted, nice guy Jim Montgomery was hired but the irony is it may have been the right move. Boston has one of the top two records in the NHL, trading places on and off with New Jersey, and is on a ridiculous league home record streak of 14 straight wins at the Garden.

The Bruins are so deep right now that they have forward Taylor Hall, the league’s No. 1 draft pick in 2010, as a third liner. Huh?

The Bruins lead the league in goals per game (4.00) and goals allowed (2.13)

“They’re firing on all cylinders in every category,” Cassidy told the Las Vegas Review-Journal. “I’m looking forward to it.”

Former Bruins coach Bruce Cassidy, shown when he was hired by Las Vegas, returns to the TD Garden tonight with the Golden Knights. (AP photo)

Of course, the irony is Cassidy has the Golden Knights, who missed the playoffs last year, atop the Western Conference at 17-7-1.

Montgomery, meanwhile, has done an absolutely sensational job. He has the Bruins playing a more wide open style while still able to take care of the back end. Of course, that’s always good for the regular season; it’s the playoffs where things get tighter and those speedskating opportunities aren’t there.

Cassidy always calls it as he sees it; that, and the team’s success, is what made him so popular with the fans.

“I think Claude laid a terrific foundation,” Cassidy said in the Review-Journal story. “We built off that. Monty’s continued to do the same.”

Cassidy will should get plenty of cheers tonight when he takes the visitors bench. It’ll feel strange for him, for sure.

Was it the right move? Tonight’s game certainly won’t indicate anything; check back with us in May and June, because that’s when things really count.

Tom King can be reached at tking@nashuatelegraph.com, or on twitter @Telegraph _TomK.