The club has completed the signing of attacking midfielder Finn Azaz from Aston Villa.
The 23-year-old joins for an undisclosed fee and has signed a four-and-a-half year contract.
The player brings a wealth of experience despite his young years. He has already clocked up over 150 career appearances and scored 25 goals.
Finn, who graduated from the West Brom Academy where he started as a nine-year-old, spent the 2020/21 season on loan at Cheltenham before joining Aston Villa permanently in the following summer.
From Villa, he gained more senior experience with a loan at Newport, where he scored seven goals in 45 matches, and he has spent the last 18 months at Plymouth Argyle, where he made 67 appearances, scored 15 goals, and was a League One promotion winner last season.
Boro Head Coach Michael Carrick said: "I'm delighted to bring Finn to the club. He's an exciting player who already comes with good experience. He's a good season so far, and we're really looking forward to working with him."
Finn, who will wear the number 20 shirt, is not eligible for tomorrow's Emirates FA Cup match against Aston Villa.