(Springfield, MO) -- If you've ever wondered what that semi next to you on the highway is hauling, an arrest today near Springfield might catch your attention.

A Missouri Highway Patrol trooper noticed an illegal license plate on a semi on Interstate 44 just east of Springfield this morning.  When he pulled the rig over, the two drivers inside became nervous, troopers say.

Sgt. Dan Bracker says the trooper also noticed some irregularities in the truck log.  The so-called "spread" trailer had hot tubs on one end and vehicles on the other.  But what was in between drew the nose of a K-9 unit. (see video)

"They made the traffic stop due to a license violation on the trailer.  They got to talking to the driver, he was very nervous.  There were multiple logbook violations.  At that point, he ran the K-9 around the trailer and it hit on it.  Brought it back here to Troop D, downloaded the vehicles, spread the trailer, and found the marijuana inside the trailer," Bracker said.

In all, 1,350 pounds of pot, packaged in 55 large bundles, were hidden in the middle section of the trailer.  Bracker says troopers believe the pot originated in Tucson or Los Angeles and was bound for the east coast, although the two men in the truck are not cooperating with the investigation. 

Bracker says the haul is worth millions if it were sold on the street.